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Kohler 12TRES Generator Set

The Kohler 12TRES is a 12 kW natural gas or propane (LP) vapor standby generator set powered by a Kohler CH 740 engine. It is available at 230/400 V, 3-phase and 50 Hz. It holds about 1.9 L (0.5 gal) of oil. Starting uses 1 battery rated 500 CCA at 12 V. The same CH 740 engine also powers generator sets from SDMO.

12 kW
Standby
0.725 L
Displacement
1.9 L
Oil capacity
3
Document types

How to read your Kohler serial & model number →

Typical fuel consumption for 10–15 kW Bi-Fuel (NG/LP) generators →

Compare with other 10–15 kW Bi-Fuel (NG/LP) generators →

Service parts for the 12TRES

Grouped by system, with how many of each the parts manual calls for.

Oil system

1 required

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

Fuelnatural gas or propane (LP) vapor
Frequency50.0 Hz
Standby power12 kW
ControllerADC-RES, ADC-RES (Advanced Digital)
Oil capacity1.9 L
Voltage options230/400 V, 50 V
Phase3
Circuit breaker20 A
Battery cranking500 CCA
Battery voltage12 V
Battery quantity1
Starting system12 V DC

Engine

Kohler CH 740
Oil capacity2.0 L
Coolant capacity0.0 L
Displacement0.725 L
Aspirationair-cooled
Rated speed3000 rpm

Same engine, other brands

1 brand

The Kohler CH 740 in this set also powers 1 generator set sold under 1 other brand. Service parts and maintenance intervals for the engine are shared; enclosure, alternator, controller and ratings are not.

BrandModels
SDMORES 12 TEC

Maintenance & consumables

for the Kohler CH 740
ItemSpecCapacityPart #Interval
Air filter—300 hr
Fuel filterfuel system—
Oil filter52 050 02-S200 hr Amazon
Batterybattery—200 hr
Beltcoupling—
Coolant—
Coolant filter—150 hr
Oil2.7 L—300 hr
Spark plug0.76 mm (0.030 in.) gap—500 hr

Service intervals

40
ItemActionHoursMonthsNotes
Oil levelCheck8 hrCheck at 8 hr. or before use
Air cleaner and precleaner (8.5/12RES)Replace100 hr12 moYearly or 100 hours; replace as necessary
Air cleaner and precleaner serviceClean100 hr12 moYearly or 100 hr.; service more frequently in dusty areas
Air cleaner and precleaner serviceReplace100 hrYearly or 100 hours, 8.5/12 kW models; replace as necessary
Air cleaner and precleaner service (8.5/12 kW)Replace100 hrYearly or 100 hours; service more frequently under dusty/dirty conditions
Change oilReplace100 hr12 moYearly or 100 hr.
Engine oilChange100 hr12 mo8.5/12RES: yearly or 100 hours
Oil coolerClean100 hr12 moYearly or 100 hours; 17/18 kW models
Oil coolerInspect100 hrYearly or 100 hours (17/18 kW models)
Oil cooler (17/18RES)Clean100 hr12 moYearly or 100 hours; inspect and clean
Air cleaner serviceClean150 hrYearly or hours shown; 17/18 kW models
Air cleaner serviceReplace150 hrYearly or 150 hours shown (300 hours also listed), 17/18 kW models
Air cleaner service (17/18 kW)Replace150 hrYearly or 150/300 hours
Change oilChange150 hrYearly or 150 hours, 17/18 kW models
Engine oil (17/18RES)Change150 hr12 moYearly or 150 hours
OilChange150 hrYearly or 150 hours; 17/18 kW models
Oil filter (17/18RES)Replace150 hr12 moYearly or 150 hours
Spark plugsClean150 hrYearly or hours shown; 17/18 kW models
Spark plugs (17/18 kW)Replace150 hrYearly or 150/300 hours
Oil filterReplace200 hr12 moYearly or 200 hours; 8.5/12 kW models
Replace filter (oil filter)Replace200 hrYearly or 200 hours (8.5/12 kW models)
Replace filter(s)Replace200 hr12 moYearly or 200 hr.
Air cleaner serviceChange300 hrYearly or hours shown; 17/18 kW models
Spark plugsCheck300 hrYearly or 300 hours; 8.5/12 kW models
Spark plugsReplace300 hrYearly or hours shown; 17/18 kW models
Spark plugs (8.5/12 kW)Replace300 hrYearly or 300 hours
Spark plugs (8.5/12RES)Check300 hr12 moYearly or 300 hours
Crankcase breather hoseCheck500 hr12 moYearly or 500 hours; 8.5/12 kW models
Crankcase breather hoseInspect500 hrYearly or 500 hours
Crankcase breather hoseOther500 hr12 moYearly or 500 hr.; follow engine manufacturer's maintenance manual
Replace spark plugsReplace500 hr
Replace stepper motor coupling and bushingReplace500 hr500 hours; authorized distributor/dealer only
Resistance readings of windings with insulation tester (Megger)Test500 hr36 mo3 yr.; with SCR assembly or rectifier and load leads disconnected
Stepper motor coupling and bushingReplace500 hr36 moAuthorized distributor/dealer only; 8.5/12 kW models
Wire-cable insulation breakdownTest500 hr36 mo3 yr. or 500 hr.
Wire-cable insulation conditionInspect500 hr36 mo3 years or 500 hours
Wire-cable insulation conditionTest500 hr3 years or 500 hours
AC electrical system general inspectionInspect3 moQuarterly
Air ducts and louvers in enclosureClean12 moYearly; service more frequently in dusty areas
Air ducts, louversClean12 moYearly

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

60
TypeItemValueUnitCondition
GapMagnetic pickup air gap0.5mm (0.020 in.)
GapSpark Plug Gap 12/17/18RES0.76mm (0.030 in.)
GapSpark Plug Gap 8.5kW0.51mm (0.020 in.)
GapSpark plug gap0.51mm (0.020 in.)
GapSpark plug gap0.76mm (0.030 in.)
GapSpark plug gap, 12/17/18RES0.76mm (0.030 in.)cold
GapSpark plug gap, 8.5 kW0.51mm (0.020 in.)cold
OtherBrush length, new19.05mm (0.75 in.)new
OtherCompression ratio8.5:1
OtherCompression ratio9.0:1
OtherFuel system leak test pressure6-8 ounces per square inch (10-14 inches water column)oz/in²LPG vapor or natural gas system
OtherOverfrequency shutdown threshold110% of system frequency setpointmore than 5 seconds, active 10s after start
OtherUnderfrequency shutdown threshold54Hzmore than 5 seconds (or below 56.5 Hz for more than 60 seconds)
PressureEngine oil pressure172--241kPa (25--35 psi)
PressureFuel system leak test (LP vapor or natural gas)6--8 ounces per square inch (10--14 inches water column)oz/in2system pressurized, soap and water solution
PressureGas fuel system leak test pressure6--8ounces per square inch (10--14 inches water column)fuel system test pressurized; use soap and water solution without ammonia or chlorine
PressureLP supply pressure1.7--2.7kPa (7--11 in. water column)
PressureNatural gas supply pressure1.2--2.7kPa (5--11 in. water column)
ResistanceBrush resistance0.1--0.2ohms (without meter lead resistance)
ResistanceCoolant temperature sensor (CTS) resistance180--200ohmsat 100 C (212 F)
ResistanceCoolant temperature sensor (CTS) resistance2100--2500ohmsat 30 C (86 F)
ResistanceMagnetic pickup resistance across QCON1 and QCON21.3--1.9kOhm
ResistanceRotor resistance4.0ohms, coldcold
ResistanceRotor resistance4.2ohms, coldcold
ResistanceStator resistance leads 1-2, 3-40.07ohms, coldcold
ResistanceStator resistance leads 1-4, 2-5, 3-6, 7-10, 8-11, 9-120.18ohms, coldcold
ResistanceStator resistance leads 11-440.14ohms, coldcold
ResistanceStator resistance leads 55-660.15ohms, coldcold
ResistanceStator resistance leads 55-660.70ohms, coldcold
ResistanceStepper motor coil resistance per half coil38.5ohms
SpeedCrank cycle15seconds crank and 15 seconds off, 3 attemptsstarting
SpeedCrank cycle15 seconds crank and 15 seconds off, 3 attemptsseconds
SpeedCut-in frequency47.5Hz50 Hz units
SpeedCut-in frequency57.5Hz60 Hz units
SpeedEngine speed, full load (mechanical governor)3600RPM (60 Hz)full load
SpeedEngine speed, no load (mechanical governor)3780RPM (63 Hz)no load
SpeedOverfrequency shutdown threshold110% of system frequency setpoint for more than 5 seconds%active 10 seconds after engine start
SpeedOverspeed shutdown threshold110% of normal running speedmore than 0.3 seconds
SpeedOverspeed shutdown threshold110% of normal running speed for more than 0.3 seconds%
SpeedOverspeed shutdown threshold115% of normal running speedrpmmore than 0.3 seconds
SpeedRated engine speed3000rpm50 Hz operation
SpeedRated engine speed3600rpm60 Hz operation
SpeedUnderfrequency shutdown thresholdbelow 54 Hz for more than 5 seconds; below 56.5 Hz for more than 60 secondsHzactive 10 seconds after engine start
TemperatureBattery heater thermostat ON / OFF16-18 °C (60-65 °F) on; 27 °C (80 °F) off°C
TemperatureCarburetor heater thermostat OFF16 ± 3°C60 ± 5 °F
TemperatureCarburetor heater thermostat ON4 ± 3°C40 ± 5 °F
TorqueAlternator assembly overbolts (reassembly)7Nm (60 in. lb.)
TorqueAlternator overbolts7Nm (5 ft. lb.)
TorqueAlternator thrubolt40Nm (28 ft. lb.)
TorqueCylinder head nuts30Nm (40.7 ft. lb.)
TorqueEngine muffler flange nuts (reassembly)24Nm (216 in. lb.)
TorqueGenerator adapter bolts (reassembly, 7/16-14 x 1.0 hex cap)40Nm (28 ft. lb.)
TorqueGenerator adapter screws40Nm (28 ft. lb.)
TorqueMuffler flange bolts24Nm (17.7 ft. lb.)
TorqueOil filter5.7--9.0Nm (4.2--6.7 ft. lb.)
TorqueRotor thrubolt (reassembly)40Nm (28 ft. lb.)
TorqueSpark Plug Torque24.4-29.8Nm (18-22 ft. lb.)
TorqueSpark plug18-22ft. lb.
TorqueSpark plug24.4--29.8Nm (18--22 ft. lb.)
TorqueSpark plug24.4-29.8Nm

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

FluidGradeStandardAmbientCapacityNotes
Engine oil5W-30API SG, SH, or SJ syntheticSynthetic oil recommended
Engine oil5W-20, 5W-30API Service Class SG or higher, synthetic-30°C to 10°CEngine Oil Selection chart; use synthetic oil
Engine oil10W-30API Service Class SG or higher, synthetic-20°C to 40°CEngine Oil Selection chart; use synthetic oil
FuelLP gas or natural gasMinimum supply pressure 7--11 in. H2O (4--6 oz./in.2); multi-fuel system field convertible
FuelLPGFuel supply pressure 1.7-2.7 kPa (7-11 in H2O); nominal fuel rating 2500 Btu/ft3 (93 MJ/m3); supply inlet 1/2 NPT
FuelNatural GasFuel supply pressure 1.3-2.7 kPa (5-11 in H2O) for 8.5/12RES, 1.7-2.7 kPa (7-11 in H2O) for 18RES; nominal fuel rating 1000 Btu/ft3 (37 MJ/m3); supply inlet 1/2 NPT
FuelNatural gas or propane (LP) vaporField-convertible multi-fuel; CARB emission certifiedClean-burning natural gas or propane (LP) vapor; air-cooled engine, no liquid coolant
Fuelnatural gas or propane (LP) vaporField-convertible multi-fuel system maintaining CARB emission certification
OtherBicarbonate of soda (baking soda) and water solutionBattery acid cleanup: 500 g (1 lb.) bicarbonate of soda to 4 L (1 gal.) water; also used to clean battery and cables
OtherPetroleum jelly, silicone grease, or other nonconductive greaseCoat battery terminals after reconnecting cables

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Fault codes

14
CodeNameMeaningSeverityAction
AFAuxiliary fault input shutdownShutdown initiated by pushing the emergency stop switch (TRES models only). Not used on RES models.ShutdownCheck the position of the emergency stop button (TRES models only).
HBHigh battery voltage warningDisplayed if engine starting battery voltage rises above 16 VDC for more than 30 seconds when engine is running.WarningCheck the battery rating and condition; check battery charger operation.
HEHigh engine temperature shutdownShutdown occurs if the engine coolant temperature exceeds the maximum for more than 5 seconds. Active after engine reaches crank disconnect speed.ShutdownCheck for blocked air inlets and exhaust outlets.
LBLow battery voltage warningDisplayed if engine starting battery voltage falls below 11 VDC for more than 30 seconds when engine is not running.WarningCheck the battery rating and condition; check battery charger operation; charge or replace battery.
LCLLow coolant levelNot used on air-cooled models.Shutdown
LOCLoss of coolantNot used on air-cooled models.Shutdown
LOPLow oil pressure shutdownShutdown occurs if a low oil pressure condition exists for more than 5 seconds. Active 30 seconds after crank disconnect speed.ShutdownCheck for leaks in lubrication system; check oil level and add oil if low.
OCOvercrank shutdownShutdown after 3 unsuccessful starting attempts (15s crank, 15s rest each). Also on locked rotor if no engine rotation sensed during cranking.ShutdownCheck fuel supply, spark plug, battery, loose connections. Contact dealer if problem continues.
OFOverfrequency shutdownShutdown occurs when governed frequency exceeds 110% of system frequency setpoint for more than 5 seconds. Active 10 seconds after engine start.ShutdownContact an authorized distributor/dealer for service if problem continues.
OSOverspeed shutdownShutdown occurs if engine speed exceeds 110% of normal running speed for more than 0.3 seconds.ShutdownContact an authorized distributor/dealer for service if problem continues.
OUOvervoltage shutdownShutdown occurs if voltage exceeds 120% of system nominal voltage for more than 2 seconds.ShutdownContact an authorized distributor/dealer for service if problem continues.
SCF0Software Communication Fault 0Indicates a software or communication problem within the controller.ShutdownReplace the controller.
UFUnderfrequency shutdownShutdown occurs if governed frequency falls below 54 Hz for more than 5 seconds, or below 56.5 Hz for more than 60 seconds. Active 10 seconds after engine start.ShutdownReduce load and restart; contact dealer if problem continues.
UUUndervoltage shutdownShutdown occurs if voltage falls below 80% of nominal system voltage for more than 10 seconds.ShutdownReduce load and restart; contact dealer if problem continues.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

12
Frequency Adjustment Procedure adjustment

Tools: frequency meter

  1. Attach a frequency meter to the AC output leads or an outlet on the load side of the generator set.
  2. Start and run the generator set, then adjust engine governor speed to set output frequency (3600 rpm for 60 Hz, 3000 rpm for 50 Hz).
Fuel Conversion Procedure (Models with Fuel Block) adjustment

⚠ Explosive fuel vapors. Use extreme care when handling, storing, and using fuels.

  1. Disable genset: master switch OFF, disconnect battery charger, disconnect battery negative lead first.
  2. Turn off fuel supply.
  3. Remove hose clamp and fuel hose from hose fitting in the fuel metering valve.
  4. Remove hose fitting from the natural gas outlet port.
  5. Remove plug from LP port; clean, apply pipe sealant, install plug into natural gas port.
  6. Clean hose fitting, apply pipe sealant, install fitting into LP port.
  7. Slide hose onto fitting and secure with clamp.
  8. For 12 kW models: connect DSAI leads together for natural gas (disconnect for LP).
  9. Connect and turn on new fuel supply; reconnect battery negative last; reconnect battery charger.
  10. Start genset and check for leaks using a gas leak detector.
Fuel Metering Valve Adjustment Procedure adjustment

⚠ Adjusting fuel metering valves on emission-certified gensets may void the emission certification. Only trained authorized technicians may adjust.

Tools: Digital voltmeter (DVM), UEGO oxygen sensor service kit GM29385, Load bank

  1. Disable genset (master switch OFF, disconnect battery charger).
  2. Remove oxygen sensor plug from exhaust manifold and install oxygen sensor.
  3. Connect oxygen sensor to engine starting battery, control module, and voltmeter.
  4. Reconnect battery charger, start genset, and run to normal operating temperature.
  5. Apply rated load; measure oxygen sensor output voltage (potential to ground).
  6. Adjust fuel metering valve to obtain specified oxygen sensor output.
  7. Seal metering valve adjustment screws with thread sealant.
  8. Remove load and cool genset 5-10 minutes; stop genset.
  9. Disconnect battery negative lead first; allow exhaust to cool.
  10. Remove oxygen sensor and reinstall exhaust plug with antiseize; reconnect battery negative lead last and battery charger.
Mechanical Governor Arm Adjustment Procedure adjustment

⚠ Accidental starting can cause severe injury or death.

Tools: Nail

  1. Make sure throttle linkage is connected to governor arm and carburetor throttle lever.
  2. Loosen the hex nut holding the governor lever to the cross shaft.
  3. Move governor lever toward carburetor as far as it will go (wide open throttle) and hold.
  4. Insert a nail into the hole in the cross shaft and rotate the shaft counterclockwise as far as it will turn; tighten hex nut and remove nail.
Voltage Adjustment Procedure adjustment

Tools: digital multimeter

  1. With the generator set off, connect a digital multimeter to the output leads or an outlet on the load side; set meter to AC voltage.
  2. Start the generator set by moving the master switch to RUN.
  3. Use the ADC controller to adjust the voltage (parameter 1P) until output voltage reaches the desired value.
  4. Adjust the voltage stability (gain, parameter 2P) to minimize light flicker.
  5. Readjust the voltage if necessary.
  6. Set the multimeter to measure frequency.
  7. Adjust engine speed to the cut-in frequency (57.5 Hz for 60 Hz units, 47.5 Hz for 50 Hz units) via engine governor speed (parameter 4P).
  8. Adjust the volts/Hz (parameter 3P) until voltage begins to drop as load is applied at cut-in frequency.
  9. Reset engine speed to operating frequency (50 or 60 Hz) via parameter 4P.
  10. Readjust voltage stability (parameter 2P) if necessary.
  11. Readjust voltage (parameter 1P) if necessary.
  12. Save settings.
  13. Stop the generator set.
Governor System Operation Test Procedure diagnostic

⚠ Hazardous voltage. Moving parts. Hot engine and exhaust system.

Tools: Voltmeter, Ohmmeter, Feeler gauge

  1. Verify carburetor throttle linkage is connected to the stepper motor.
  2. Check for broken or loose wiring if the stepper motor moves erratically.
  3. Check stepper motor operation at startup: it should move fully open then to fully closed position.
  4. Stop genset and check magnetic pickup resistance at QCON1 and QCON2 (1.3--1.9 kOhms).
  5. Verify magnetic pickup voltage output (1.75 VAC minimum during cranking).
  6. Check/adjust magnetic pickup air gap to 0.5 mm (0.020 in.).
  7. Disconnect magnetic pickup leads, open circuit breaker, and test controller governing function.
  8. Check stepper motor coil resistance across pins 2-3 and 1-4 (38.5 ohms per half coil).
Resetting Controller after a Fault Shutdown diagnostic
  1. Move master switch to OFF/RESET
  2. Disconnect generator set from load using line circuit breaker or ATS
  3. Identify and correct the cause of the fault shutdown
  4. Start generator set by moving master switch to RUN; test operate
  5. Move master switch to OFF/RESET
  6. Reconnect generator set to load
  7. Move master switch to AUTO for remote start
Rotor Test Procedure diagnostic

⚠ Hazardous voltage will cause severe injury or death.

Tools: Ohmmeter, Megohmmeter

  1. Disable genset and disconnect battery negative lead first.
  2. Remove the brush cover from the alternator end bracket.
  3. Raise brushes from slip rings; measure rotor resistance between the two slip rings.
  4. Perform megohmmeter test: apply 500 VDC to one slip ring and the rotor poles or shaft.
  5. Reading of approx. 500 kOhms or higher indicates a good rotor; repair or replace if less.
SCR Module Test Procedure diagnostic

⚠ SCR module may be damaged if power supply is connected incorrectly. Connect negative battery lead to positive terminal on SCR module.

Tools: Ohmmeter, 12-volt test lamp (or voltmeter), 12-volt DC power source, 100--500 ohm resistor, Jumper

  1. Set ohmmeter to R x 1.
  2. Check (+) to (--) on SCR module: high resistance one direction, low the other.
  3. Check AC1 to (+): high resistance both directions.
  4. Check AC1 to (--): high resistance one direction, low the other; repeat for AC2.
  5. Check G1 to (+): low resistance both directions; repeat for G2.
  6. Connect negative DC lead to positive (+) terminal on SCR module.
  7. Connect positive lead with lamp in series to AC1 (lamp should not glow); jumper with resistor from positive to G1 (lamp should glow).
  8. Repeat step 9/10 for AC2 and G2; replace module if any check fails.
Separate Excitation Procedure diagnostic

⚠ Hazardous voltage will cause severe injury or death. Have qualified personnel perform testing.

Tools: DC ammeter, 20-amp fuse, 12-volt automotive battery

  1. Disconnect black FN and FP leads from alternator at SCR module (+) and (--) terminals.
  2. Connect a DC ammeter, 20-amp fuse, and 12-volt battery to FP and FN brush leads; record reading.
  3. Start engine and check ammeter reading remains stable (increasing = shorted rotor; decreasing/unstable = running open).
  4. Check for AC output across stator leads and compare to specifications.
  5. If rotor and stator are good, check wiring, fuses, SCR module, and controller settings.
Stator Continuity and Resistance Tests diagnostic

⚠ High voltage test. Follow test equipment manufacturer instructions; improper procedure can damage equipment.

Tools: Ohmmeter, Megohmmeter

  1. Disable genset and disconnect all stator leads before all stator tests.
  2. Set ohmmeter to R x 1 and zero it by holding leads together.
  3. Check cold resistance of stator windings at leads 1-2, 3-4, and 55-66 (single-phase).
  4. Use a megohmmeter: apply 500 VDC to a stator lead and the stator frame; repeat for each coil.
  5. A reading of approximately 500 kOhms or higher indicates a good stator; repair/replace if less.
Air Cleaner Service Procedure maintenance

⚠ A sudden backfire can cause severe injury or death. Do not operate with air cleaner removed.

  1. Disable the generator set (master switch OFF/RESET, disconnect battery charger, disconnect battery negative lead first).
  2. Remove foam precleaner and paper element.
  3. Wash and oil the foam precleaner in warm soapy water, rinse, air dry, saturate with new engine oil, squeeze out excess.
  4. Replace paper element if dirty, bent, or damaged; do not wash or blow it out.
  5. Reinstall precleaner over paper element; install element, cover, nut, and cover; finger-tighten knob.
  6. Enable the generator set (reconnect battery negative lead last, reconnect battery charger).

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

VoltagePhaseConnectionLeadsNotes
110Single (L0-L1)Factory two-pole circuit breaker50 Hz; not reconnectable
110Single (L0-L2)Factory two-pole circuit breaker50 Hz; not reconnectable
120Single (L0-L1)Factory two-pole circuit breaker; 4 stator leads1, 2, 3, 4 (output); 11, 44, 55, 66 (sensing/supply)60 Hz, 110/220 and 120/240 V, 3-wire configuration; not reconnectable
120Single (L0-L2)Factory two-pole circuit breaker60 Hz; not reconnectable
120 VACUtility Power terminals on field-connection terminal blockUtility power circuit must be backed up by the generator set
220Single (L1-L2)Factory two-pole circuit breaker50 Hz; not reconnectable
230/400ThreeFactory connected for 230/400 V, 50 Hz12 leads (1-12 output; V7, V8, V9, 55, 66 sensing/supply)12TRES 3-phase; not reconnectable
240Single (L1-L2)Factory two-pole circuit breaker60 Hz; not reconnectable

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

What size generator is the Kohler 12TRES?

The Kohler 12TRES is rated 12 kW standby.

What engine is in the Kohler 12TRES?

The Kohler 12TRES is powered by the Kohler CH 740 engine.

What fuel type does the Kohler 12TRES take?

The Kohler 12TRES runs on natural gas or propane (LP) vapor.

How much oil does the Kohler 12TRES take?

The Kohler CH 740 engine in the Kohler 12TRES has an oil capacity of 2.0 liters.

What voltages is the Kohler 12TRES available in?

The Kohler 12TRES is offered in 230/400 V, 50 V, 3-phase.

What battery does the Kohler 12TRES use?

The Kohler 12TRES uses 1 battery, 12 V each, 500 CCA, per the manufacturer specification sheet. The starting system is 12 V DC.

What oil filter fits the Kohler 12TRES?

The Kohler 12TRES uses oil filter part number 52 050 02-S.

Troubleshooting

6

Fault codes

CodeMeaningRemedy
AFAuxiliary fault input shutdown — Indicates a shutdown initiated by pushing the emergency stop switch. (TRES models only) Not used on RES models.Check the position of the emergency stop button. (TRES models only)
HEHigh engine temperature shutdown — Shutdown occurs if the engine coolant temperature exceeds the maximum temperature for more than 5 seconds. This function becomes active after the engine reaches the crank disconnect speed.Check for blocked air inlets and exhaust outlets.
LOPLow oil pressure shutdown — Shutdown occurs if a low oil pressure condition exists for more than 5 seconds. This function becomes active 30 seconds after the engine has reached crank disconnect speed (30 second inhibit). Note: The low oil pressure shutdown does not protect against low oil level. Check the oil level at the engine.Check for leaks in the lubrication system.; Check the oil level and add oil if the level is low.
OCOvercrank shutdown — Shutdown occurs after 3 unsuccessful starting attempts. The crank cycle is set for three starting attempts of 15 seconds cranking and 15 seconds rest.Check the fuel supply, spark plug, and battery.; Check for loose connections.; Contact an authorized distributor/dealer for service if problem continues.
OCLocked rotor — The generator set also shuts down on OC if no engine rotation is sensed during cranking. Shuts down 3 seconds after the fault is detected.
OFOverfrequency shutdown — Shutdown occurs when the governed frequency exceeds 110% of the system’s frequency setpoint for more than 5 seconds. This function becomes active 10 seconds after engine start (10 second inhibit).Contact an authorized distributor/dealer for service if problem continues.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing. Full Kohler 12TRES troubleshooting guide (224 entries) →

Parts

250
Part #DescriptionQtySystem
103-0731Gasket, Gearcase1Gasket Amazon eBay
103-0733Gasket, Gearcase Backplate1Gasket Amazon eBay
103-0746Gearcase (Includes Oil Seal and Oil Fill Tube)Seal Amazon eBay
110-1718Head, Cylinder Gasket, Cylinder Head2Gasket Amazon eBay
110-2987Gasket, Cylinder Head2Gasket Amazon eBay
110-3225Gasket, Cylinder Head1Gasket Amazon eBay
12 050 01Oil Filter1Oil filter Amazon eBay $19.06 KuduParts $11.00 FridayParts $33.98
12 050 01-SFilter, oil1Oil filter Amazon eBay $19.06 KuduParts $32.00 FridayParts $33.98
12 132 02-SSpark Plug1Spark plug buy
120-0491Pump, Oil1Pump Amazon eBay $30.00
120-1041Bearing, Oil Pump Idler Gear (Semi Finished)1Pump Amazon eBay
130-07558racket, Mounting Heater, Tank - 850 Watt, 115 Volt (Includes Hose Connector, Cord and Mounting Strap)1Hose Amazon eBay
130-2500Guard, Belt (Left Side)1Belt Amazon eBay
134-1437Spring - Injecion Pump Lever1Pump Amazon eBay
140-1787Hood, Air Cleaner1Air filter Amazon eBay
140-1791Indicator Service1Sensor Amazon eBay
140-1841Cleaner. Air (Includes Element)1Air filter Amazon eBay $50.00
140-2174Cleaner, Air - Oil Bath Band. Mount ing1 2Air filter Amazon eBay
140-2234Tube. Air InletHose Amazon eBay
141-0982Gasket2Gasket Amazon eBay
141-0983Gasket, Carburetor1Gasket Amazon eBay
147-0436Seal, Injector6Seal Amazon eBay
147-0465-12Pump, Fuel Injection (See Separate Page for Components)1Pump Amazon eBay
147-0701Injector, Fuel (Includes Seal)6Seal Amazon eBay
147-0856Injector, Fuel (Includes Parts Marked #)2Injector Amazon eBay FridayParts $72.02
147-0864#O'Ring, Injector2Injector Amazon eBay
147-0865#O'Ring, Injector2Injector Amazon eBay
147-2715Remote Fuel Pump Kit EFI (HGJAA)1Fuel pump Amazon eBay
149-1445Filter1Fuel filter Amazon eBay $19.95
149-1446Gasket, Cover1Gasket Amazon eBay
149-1828Pump, Fuel (Electric)1Pump Amazon eBay $39.59 FridayParts $40.41
149-1914-04Element, Filter (Includes O-fling Seal) (2 M~CPXI)1Seal Amazon eBay
149-1920Plate, Mounting - Fuel Filter Elbow, Hose - Male1Fuel filter Amazon eBay
149-1921Plate, Mounting - Fuel Filter Elbow, Hose - Male1Fuel filter Amazon eBay
149-1922Spacer, Mounting - Fuel Filter1Fuel filter Amazon eBay
149-1949Head Assembly. Replacement (Includes Vent Plug. O-Ring Seals. Pump Assembly and Tube) Seal)1Seal Amazon eBay
149-1953Drain Assy (Includes Knob and Seal)1Seal Amazon eBay
149-2100Filter Assembly, Fuel Element. Filter1Fuel filter Amazon eBay
149-2106Element1Fuel filter Amazon eBay $34.99 NAPA $61.61 KuduParts $68.00
149A159Gasket - Spacer - BLAKING mfr. pump only2Gasket Amazon eBay
149A551Lever, Hand Primer - ONAN mfr. pump only1Pump Amazon eBay
149D693Pump, Fuel - ONAN mfr., with primer lever - Replaces earlier atyle pumps used, of any manufacture1Pump Amazon eBay
149K526Repair Kit, Fuel Pump1Fuel pump Amazon eBay
149K74Repair Kit, Fuel Pump - Includes parts marked (* anda) - For AC mfr., BLAKING mfr. or ONAN mfr. pumps1Fuel pump Amazon eBay
151-0437Kit, Throttle Modification (Fuel Injection Pump)1Fuel pump Amazon eBay
1512-0154Belt Fan1Belt Amazon eBay
154-3067-02Manifold Assy, Intake (Includes Hose Connector)1Hose Amazon eBay
154-3085Gasket, Intake Manifold2Gasket Amazon eBay
154P570Union, Manifold Flange2Exhaust Amazon eBay
155-2073Gasket, Exhaust Pipe1Gasket Amazon eBay
155-2415Seal, Muffler Support18Seal Amazon eBay
155-2619Spec D, Exhaust Manifold) *Gasket. Elbow - Exhaust (WC 0)1Gasket Amazon eBay
15SA47Tube, Flexible Exhaust2Exhaust Amazon eBay
165-2203Gasket, Manifold - Exhaust (&xx A-C):Gasket Amazon eBay
167-0272Spark plug2Spark plug Amazon eBay
168-0174Kit, Gasket - Valve Grind1Gasket Amazon eBay
185-2175Gasket1Gasket Amazon eBay
185-2199Band, Mounting - Air Cleaner1Air filter Amazon eBay
185-2203Gasket, Manifold - Exhaust (&xx A-C)1Gasket Amazon eBay
185-2239Clamp, Hose1Hose Amazon eBay
185-2240Clamp, Hose2Hose Amazon eBay
185-2266Alternator (12 VDC) (See Separate Page for Components)1Alternator Amazon eBay
185-2284Gasket2Gasket Amazon eBay
185-2300Clamp, Hose1Hose Amazon eBay
185-2311Housing, Thermostat1Thermostat Amazon eBay FridayParts $27.75
185-2421Hose, Rubber - Overflow1Hose Amazon eBay
187-6224Gasket, Rocker Cover1Gasket Amazon eBay
187-6230Gasket, Cylinder Head (1)1Gasket Amazon eBay
187-6238Gasket, Breather Plate1Gasket Amazon eBay
191-1368Arm, Alternator Adjusting1Alternator Amazon eBay
191-1872Alternator (12 VDC) (Gl)1Alternator Amazon eBay
191-1983-01Alternator1Alternator Amazon eBay
191-2085Strap, Alternator Adjust1Alternator Amazon eBay
193-0247'Sender, Temperature - Engine Coolant1Sensor Amazon eBay
193-0469Sensor, Map1Sensor Amazon eBay
193-0480Sensor, Manifold Air Temperature1Sensor Amazon eBay
227473Cover, brush holder1Cover eBay
229239Washer, overbolt4Washer eBay
229335Bracket, brush holder1Bracket eBay
238150Spring2Spring eBay
238214Guard, generator fan1Guard eBay
238247Retainer, wire1Retainer eBay $4.95
238248Shim, brush holder2Shim eBay $19.99
239282BRUSH2Brush Amazon eBay $37.28
24 032 19-SSeal, oil front1Seal FridayParts $10.99
24 050 01-SFilter, breather8Filter buy
24 083 02Precleaner element1Air filter buy
24 083 02-SPrecleaner8Air filter buy
24 083 05-SPrecleaner8Air filter buy
24 083 08Air cleaner element1Air filter buy
24 083 08-SElement, air filter1Air filter buy
24 083 09-SElement, air filter1Air filter buy
24 153 01-SO-ring1Seal buy
24 153 08-SO-ring1Seal buy
24 153 21-SO-ring, oil cooler1Seal buy
24 393 51-SKit, oil pump assembly (includes items 12, 13)1Pump buy
24 590 01-AOil Cooler, 14RCA/LOil cooler buy
24 590 27DipstickOil dipstick buy
24 590 29Oil Fill1Oil fill buy
241927Sensor, speed1Sensor Amazon eBay $75.00
25 032 06-SSeal, oil1Seal FridayParts $11.90
25 099 26-SSwitch, oil pressure1Sensor buy
25 132 14-SSpark plug2Spark plug buy
25 158 08-SBushing, linkage retaining4Bushing buy
25 435 06-SKit, starter solenoid1Kit buy
254821Relay, 20A1Relay eBay
256466O-ring1O ring Amazon eBay
267491Screw, hex cap, 1/4-20 x 1.01Screw eBay
269190Connector, 6 pin, P101Connector eBay
269373Alternator Assembly1Alternator Amazon eBay
278774Connector, 20 pin, J41Connector eBay
278775Connector, 20 pin, P11Connector eBay
278877Cover, brush holder1Cover eBay
300-2880Board, Voltage Regulator (VR21)1Avr Amazon eBay FridayParts $350.50
300-2906Board Assy, Printed Circuit - Over/Under Volt Sensor (A17)iSensor Amazon eBay
302-0750'Sender, Tachometer1Sensor Amazon eBay
304A66Resistor, 4xELI1Resistor Amazon eBay
305-0491REGULATOR. 305-04911Avr Amazon eBay
305-0901Sensor, Low Battery Voltage1Sensor Amazon eBay
307-1061Relay, Starter Protection1Starter Amazon eBay
307P820Relay, Adjustabe Start Disconnect & Crankshaft Limiter1Relay Amazon eBay
309-0178Switch, High Water Temperature Top Mounted On Water Outlet Housing1Sensor Amazon eBay $350.00
309-0179Switch, High Water Temperature (Standard Part) Side Mounted On Water Outlet Housing1Sensor Amazon eBay
309-0269Sender, Temperature-Lo Engine1Sensor Amazon eBay $239.00
322-17Bulb, (2) Panel ( I ) Pilot2Lamp Amazon eBay
322P69Bracket, Mounting - Engine1Bracket Amazon eBay
323-1591# Plug, Seal (E1)1Seal Amazon eBay
323-1708# Seal, Cable (P8)4Seal Amazon eBay
332AI006Block, Terminal1Block Amazon eBay
332AI009Block, Terminal1Block Amazon eBay
345079Relay (being replaced by GM50772)1Kit Amazon eBay
358014Stator assembly1Stator eBay
358054Bracket, end1Bracket eBay
358056Bracket, sensor mounting1Bracket eBay
358066Actuator, magnetic1Actuator eBay
3580723/8"-16 UNC-2A THD Thrubolt1Bolt Amazon eBay
358086Box, silkscreen1Box eBay
358091Harness, controller (includes 43--48)1Harness eBay
358145Panel, controller bottom1Panel eBay
420A248Air filter1Air filter Amazon Amazon eBay eBay
501-022545' Lg - With Both Ends 1/8' NPT Male Fittings1Belt Amazon eBay
501-0227Line, Fuel - Flexible (24' La x 1/8' NPT Male x-1/8° NPT Male)1Hose Amazon eBay
502-0068Tee (3/8' x 5/8' x 5/8') to1Hose Amazon eBay
502-0313Elbow, Hose − 90° (1/8” Pipe to 1/4” Hose)1Hose Amazon eBay
502-0433[;b'$P&x 5/16 ID Hose]1Hose Amazon eBay
502-0613Connector, Hose1Hose Amazon eBay
502-0869Connector (3/8')1Hose Amazon eBay
502-0870Tee, Hose1Hose Amazon eBay
502-1314Connector, Hose1Hose Amazon eBay
503-0183Clamp, Hose1Hose Amazon eBay
503-0365Clamp, Hose1Hose Amazon eBay
503-0594Hose, Rubber - Preformed1Hose Amazon eBay
503-059bHose, Rubber - Preformed1Hose Amazon eBay
503-0685Clamp, Hose1Hose Amazon eBay $15.00
503-1058Spacer, Fan Hose, Radiator - Upper1Hose Amazon eBay
503-1062Hose - Intake Manifold Water Pump (3/8' ID)1Hose Amazon eBay
503-1074Hose Reducer1Hose Amazon eBay
503-1084Elbow. ReducerHose Amazon eBay
503-1250Hose, Water Bypass (5/8' Ill)1Hose Amazon eBay
503-1251Hose, Water Bypass (5/8' 10]1Hose Amazon eBay
503-1450Hose, Cleaner - Air1Hose Amazon eBay
503-1552-01Ho!M? (5/8' ID X 14')2Hose Amazon eBay
503-2126Hose, Vacuum1Hose Amazon eBay
503-365Clamp, Hose2Hose Amazon eBay
505-0180Plug, Pipe (1-1/4"), Air Cleaner Adapter and Intake Manifold1Air filter Amazon eBay
505-382Nipple, Exhaust(3"x 2-5/8")2Exhaust Amazon eBay
505-4Hose (Order 6 “of Bulk Hose Number 503-324)I 9Hose Amazon Amazon eBay eBay
509-0125Key, Handle - Screw, Lock (3/8 - 16 x .75")1Seal Amazon eBay
509-0191Seal, Oil (Includes Wear S1eeve )1Seal Amazon eBay
509-0196O'Ring1Seal Amazon eBay
511-0112Belt, Fan1Belt Amazon eBay
515-0094Key, Crankshaft Woodruff Belt1Belt Amazon eBay
52 099 08-SSwitch, oil pressure1Sensor buy
520-2403Stud, Injection Pump (M8)3Pump Amazon eBay
718-1069Fan Pldl@y Sell. Vee Smwv, Cap Hex Head (M8 X I 25 X 25]1Belt Amazon eBay
750-1004Nut, Hex (M6 x 1) Washer, Lock - Spring (M6) Adapter, Hose Hose, Rubber - Preformed1Hose Amazon eBay
ADV-6823-AAir Filter, Spark Plug Location1Air filter Amazon eBay
BKR-8YU11Spark Plug, CH20/CH7404Spark plug Amazon eBay
GM102176Oil pressure sensor boot1Sensor Amazon eBay
GM103743Emergency Stop Switch (optional)1Emergency stop switch Amazon eBay $59.99
GM111084Shutdown Switch1Shutdown switch Amazon eBay
GM11720Elbow, exhaust tube1Elbow eBay
GM20748Boot, battery lug1Boot Amazon eBay
GM20990Gasket4Gasket Amazon eBay
GM28823Sensor, oil temperature1Sensor Amazon eBay $50.00
GM28981UEGO sensor interface harnessSensor eBay
GM29253-GA2Controller Wiring Diagram1Controller wiring diagram Amazon eBay
GM29358-BPoint-to-Point Wiring Diagram, Single Phase1Point-to-point wiring diagram Amazon eBay
GM29385UEGO oxygen sensor service kitSensor eBay
GM29983Shield, heat1Shield eBay
GM33146Boot, battery lug1Boot Amazon eBay
GM33829Kit, battery cable (prior to build date of May 1, 2004)1Kit eBay
GM39500Arrester, spark1Arrester eBay
GM515593/8"-16 UNC-2A THD Thrubolt1Thrubolt Amazon eBay
GM80980Brush(es)1Brush Amazon eBay
GM90969-KP1-QS3" Concrete Mounting Pad (only comes in quantities of 5)Physical Amazon eBay
GM90969-KP2-QS4" Concrete Mounting Pad (only comes in quantities of 5)Physical Amazon eBay
GM92228-KP1-QS3" Concrete Mounting Pad (only comes in quantities of 5)Physical Amazon eBay
GM92228-KP2-QS4" Concrete Mounting Pad (only comes in quantities of 5)Physical Amazon eBay
KO3226Electric Starter Service Kit1Battery Amazon eBay
RSP-FT-02-US-91Pack first: complete service kit comprising air filter, air pre filter, spark plugs and oil filter.Air filter Amazon eBay
RSP-FT-04-US-91Pack first: complete service kit comprising air filter, air pre filter, spark plugs and oil filter.Air filter Amazon eBay
X-22-24Washer, lock #4, internal tooth2Hardware Amazon eBay
X-25-68Washer, plain, .281 ID x .625 in. OD4Washer eBay
X-49-1Screw, pan head machine, #6-32 x 0.3122Screw eBay
X-49-35Screw, pan head machine, #4-40 x 0.8752Screw eBay
X-6003-126Conduit, convoluted1Conduit eBay
X-6003-46Conduit, convoluted1Conduit eBay
X-634-5Bushing, nylon, 0.375 ID1Bushing eBay
X-6422-31SealSeal eBay
X-67-113Screw, self-tapping, 10-32 x 0.3758Screw eBay
X-67-115Screw, self-tapping, 1/4-202Screw eBay $22.46
X-722-8Clamp, muffler, 1.37 in.1Clamp eBay
X-781-8Rivet, 0.187 pop diameter10Rivet eBay
X-97-13Block Heater, 208--240 V6Block heater Amazon eBay
098-7130Label, Warning Heat1Service part / kit Amazon eBay
098-7369-01HDCAC2Service part / kit Amazon eBay
098-7374Label, Warning1Service part / kit Amazon eBay
098-7375Label, Switch1Service part / kit Amazon eBay
098-7376Label, Circuit Breaker1Service part / kit Amazon eBay
098-7398-01HDCAA2Service part / kit Amazon eBay
098-7398-02HDCAB2Service part / kit Amazon eBay
098-7399-0145A, 2 Pole1Service part / kit Amazon eBay
098-7399-0250A, 2 Pole1Service part / kit Amazon eBay
098-7461Label, Warning Hazardous Voltage1Service part / kit Amazon eBay
098-7462Label, Service Information Label, Model Ident1Service part / kit Amazon eBay
098-7463Label, Fuel Attachment1Service part / kit Amazon eBay
098-7464Label, Coolant Drain1Service part / kit Amazon eBay
098-7465-03Label, Control Face1Service part / kit Amazon eBay
098-7466Label, Control Rear1Service part / kit Amazon eBay
098-7497-01Label, Warning Install1Service part / kit Amazon eBay
098-7498-01Label, Warning Hazardous1Service part / kit Amazon eBay
098-7515-01Label, Warning Voltage1Service part / kit Amazon eBay
1-24-67Crankshaft1Service part / kit Amazon eBay
10-24-658Air Intake1Service part / kit Amazon eBay
101-0439Plate, Rear Bearing Bearing, Crankshaft1Service part / kit Amazon eBay NAPA $95.66
102-0778Adapter, Pipe - Oil Drain1Service part / kit Amazon eBay
104-0032Gear, Crankshaft1Service part / kit Amazon eBay NAPA $260.36
104-0091Washer, Flat (Special)4Service part / kit Amazon eBay
104-1953Washer, Flat (1/2' ID x 2.25' OD)1Service part / kit Amazon eBay
104-1958Marked *) Spec A/B Begin Spec C *Pulley Assy, Drive (Includes1Service part / kit Amazon eBay
104-2000Marked *) Spec A/B Begin Spec C *Pulley Assy, Drive (Includes1Service part / kit Amazon eBay
105-0058Plunger, Camshaft1Service part / kit Amazon eBay
105-0059Spring, Plunger1Service part / kit Amazon eBay
105-0508Shaft, Idler Gear1Service part / kit Amazon eBay
105-0513Gear, Idler (Includes Finished 8earing)1Service part / kit Amazon eBay
105-05198earing, Idler Gear (Semi Finished)1Service part / kit Amazon eBay
105-0541Washer, Thrust1Service part / kit Amazon eBay
105-0641Gear (Includes Spacer and Plate)1Service part / kit Amazon eBay
105-0676Camshaft1Service part / kit Amazon eBay

Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.

Available documents

Operator's manual (Kohler)Operator's manual — 12 RES Operation (Kohler)Operator's manual — RES with ADC Operation (Kohler)Operator's manual — tp6515 (Kohler)Reference — tp6514 (Kohler)Parts manual — 8.5-12 RMY RES Parts Manual (Kohler)Parts manual — engine controls stepper motor, governor (Kohler)Parts manual — tp5868Service manual — tp6196 (Kohler)Service manual — tp6792 (Kohler)

This page was generated from the 10 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.