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Cummins/Onan MDKB Troubleshooting

Cummins/Onan MDKB troubleshooting: 99 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.

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Troubleshooting

99

Fault codes

CodeMeaningRemedy
nkShutdown due to high engine temperature
Two blinksShutdown due to low oil pressure
Three blinksA service faultPress Stop once to cause the two-digit shutdown code to blink. (Pressing Stop again will stop the blinking.) The two-digit code consists of 1 to 7 blinks, a brief pause, and then 1 to 9 blinks. The first set of blinks represents the tens digit and the second set of blinks the units digit of the shutdown code number.
Four blinksShutdown due to a failure to start within the time allowed for cranking.
Seven blinksShutdown due to a loss of raw water flow for engine and exhaust cooling.
Overcrank-CODE NO. 4Cranking time exceeded 20 to 60 seconds, depending on engine temperatureDe-energize the PTO clutch, if so equipped. Check fuel level and refill as necessary. (Note: The generator set fuel pickups are probably higher than the propulsion engine fuel pickups.) Open any closed fuel supply and return valves. Prime the engine fuel system for at least 30 seconds (p. 3-3). Service as necessary by cleaning and tightening battery connections, recharging or replacing the battery or replacing damaged battery cables (p. 4-2). Remove combustion air or exhaust system blockages. Check all fuel fittings for fuel and air leaks and tighten as necessary. Replace fuel filters (p. 4-6). Check for contaminated fuel by connecting to a source of known fuel quality. Change the engine oil to
Fault NumberALARM status lamp on the Digital Display will blink and the LCD screen will display the Fault Number, a description of the Fault and the hour in total generator set running time when the Fault occurred (Figure 2-4). The fault will be displayed until it is cleared. Touch any button to clear the fault. The display will turn off in 5 minutes after the fault has been cleared.See Page 2-6 to display any of the last five faults in fault history.
Fault NumberThe amber status lamp on the control switch will repeatedly blink sets of 3, 4, 5 or 7 blinks.One blink: No fault. Two blinks: Over-speed trip. Three blinks: Low oil pressure trip. Four blinks: High coolant temperature trip. Five blinks: Low fuel level trip. Seven blinks: Generator set shutdown due to a fault.
1HIGH ENGINE TEMPERATURE—CODE NO. 1 (Engine coolant temperature exceeds design limit)1. Check for and clean a blocked sea water strainer. If above the water line, fill the strainer with water to assist priming. 2. Check engine coolant level and add coolant as necessary. 3. Check for kinked or leaking hoses and reconnect, reroute or replace. 4. Check the V-belt that drives the coolant pump and service as necessary (p. 4-13). 5. Inspect the siphon break for proper operation (p. 4-8). 6. Check for a worn raw water impeller and replace as necessary (p. 4-12). 7. Clean the heat exchanger (p. 4-8). 8. Check the bottom of the hull for any blockage at the through-hull fitting. 9. Replace the coolant thermostat, which might not be opening fully (p. 4-14). 10. Drain and clean the coolant system to remove coolant passage fouling (Page 4-7).
2LOW OIL PRESSURE—CODE NO. 2 (Low oil pressure)Check the engine oil level and add or drain oil as necessary (p. 4-3). Repair any oil leaks.
3SERVICE CHECK—CODE NO. 3 (A fault with a 2-Digit Fault Code Number occurred)Check the 2-Digit fault code by Pushing and Releasing Stop. The 2-Digit fault will be one of the following in this table. (Does not apply to Digital Display.)
4OVERCRANK—CODE NO. 4 (Cranking time exceeded 20 to 60 seconds, depending on engine temperature)1. De-energize the PTO clutch, if so equipped. 2. Check fuel level and refill as necessary. (Note: The generator set fuel pickups are probably higher than the propulsion engine fuel pickups.) 3. Open any closed fuel supply and return valves. 4. Prime the engine fuel system for at least 30 seconds (p. 3-3). 5. Service as necessary by cleaning and tightening battery connections, recharging or replacing the battery or replacing damaged battery cables (p. 4-2). 6. Remove combustion air or exhaust system blockages. 7. Check all fuel fittings for fuel and air leaks and tighten as necessary. 8. Replace fuel filters (p. 4-6). 9. Check for contaminated fuel by connecting to a source of known fuel quality. 10. Change the engine oil to oil of the proper viscosity for the ambient temperature. High oil viscosity can slow down cranking speed.
7LOSS OF RAW WATER FLOW—CODE NO. 7 (Low raw water pressure in heat exchanger)1. Open the sea cock. 2. Check for a blocked sea water strainer and clean it out. If above the water line, fill the strainer with water to assist priming. 3. Check for kinked or leaking hoses and reconnect, reroute or replace. 4. Check for a worn raw water impeller and replace as necessary (p. 4-12). 5. Check the bottom of the hull for any blockage at the through-hull fitting.
12HIGH AC VOLTAGE—CODE NO. 12 (After voltage regulation was enabled Output Voltage jumped to more than 125% of rated for 75 milliseconds or to more than 115% of rated for 3 seconds)1. Check for a tripped generator set circuit breaker, reset if necessary, and run with fewer loads. (A breaker tripping under load can cause generator set voltage to overshoot.) 2. Check all fuel fittings and filters for fuel and air leaks and tighten as necessary. (Air bubbles can disrupt generator set frequency/voltage.) 3. Prime the engine fuel system for at least 30 seconds (p. 3-3).
13LOW AC VOLTAGE—CODE NO. 13 (After voltage regulation was enabled Output Voltage fell to less than 90% of rated for 5 seconds)1. Push the generator set line circuit breaker OFF and disconnect the PTO, if so equipped. If the generator set now runs and voltage and frequency are normal, reduce the number of electrical and mechanical (PTO) loads. 2. Check the fuel tank and fill as necessary. (Note: The arrangement of pickup tubes in the fuel supply tank probably is such that the generator set will run out of fuel before the propulsion engines.) 3. Check all fuel fittings and filters for fuel and air leaks and tighten as necessary. (Air bubbles can disrupt generator set frequency/voltage.) 4. Replace fuel filters (p. 4-6).
CODE NO. 14After the starter was engaged Frequency jumped to more than 70 Hz for 40 milliseconds or to more than 2% over nominal for 6 seconds1. Check for a tripped generator set circuit breaker, reset if necessary, and run with fewer loads. (A breaker tripping under load can cause generator set frequency to overshoot.) 2. Check all fuel fittings and filters for fuel and air leaks and tighten as necessary. (Air bubbles can disrupt frequency.)
CODE NO. 15During normal operation Frequency fell to less than 90% of nominal for more than 8 seconds1. Push the generator set line circuit breaker OFF and de-energize the PTO clutch, if so equipped. If the generator set now runs, reduce the number of electrical and mechanical (PTO) loads, especially those with high motor starting loads, such as air conditioners. 2. Check the fuel tank and fill as necessary. (Note: The arrangement of pickup tubes in the fuel supply tank probably is such that the generator set will run out of fuel before the propulsion engines.) 3. Prime the engine fuel system for at least 30 seconds (p. 3-3). 4. Remove combustion air or exhaust system blockages. 5. Check all fuel fittings for fuel and air leaks and tighten as necessary. (Air bubbles can disrupt frequency.) 6. Replace fuel filters (p. 4-6). 7. Check for contaminated fuel by connecting to a source of known fuel quality.
CODE NO. 22Maximum allowable time at full-duty cycle was exceeded1. Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. 2. Check the fuel tank and fill as necessary. (Note: The arrangement of pickup tubes in the fuel supply tank probably is such that the generator set will run out of fuel before the propulsion engines.) 3. Remove combustion air or exhaust system blockages. 4. Check all fuel fittings for fuel and air leaks and tighten as necessary. 5. Replace fuel filters (p. 4-6). 6. Check for contaminated fuel by connecting to a source of known fuel quality.
14OverfrequencyCheck engine speed, loads, governor actuator operation, fuel supply, control plugs fully seated, quad leads fully seated in connector to control, quad winding resistance
15UnderfrequencyCheck engine speed, loads, governor actuator operation, fuel supply, control plugs fully seated, quad leads fully seated in connector to control, quad winding resistance
17OverprimeCheck battery voltage, fuel supply, start/stop switch (local and remote), shorted wiring
22Actuator OverloadCheck load, fuel supply, intake restriction, governor actuator operation; Perform checks in step 01; Check exhaust back pressure; Perform checks in step 02; Check field windings, proper field resistance reading, open to ground, brush condition and contact
23Faulty Oil Pressure SenderCheck oil level, grounded or shorted sender lead, sender resistance (low); Perform checks in step 01; Check oil pressure (mechanical)
24Faulty Temperature SenderCheck coolant level, open or loose sender lead, sender resistance (high); Perform checks in step 01; Check coolant temperature
27Loss of Voltage SenseCheck AC output, sense lead connections, control plugs fully seated, sense leads fully seated in connector to control, field windings, proper field resistance reading, open to ground, brush condition and contact, grounded or shorted main windings
29High Battery VoltageCheck battery voltage, battery connections, battery charge rate
35Control Card EE ChecksumCheck verify fault
36Engine StoppedCheck fuel supply, mechanical engine damage, output voltage, loads, quad leads fully seated in connector to control, control plugs fully seated; Perform checks in step 01; Check governor actuator operation, field windings, proper field resistance reading, open to ground, brush condition and contact, grounded or shorted quad windings
37Invalid Set ConfigurationCheck configuration number
38Field OverflowCheck output voltage, frequency, loads, air inlet; Perform checks in step 01; Check field windings, proper field resistance reading, open to ground, brush condition and contact, main stator resistance
41Grounded RotorCheck fuel supply, field windings, proper field resistance reading, open to ground, brush condition and contact
42Control Card ROMCheck verify fault
43Control Card RAMCheck verify fault
45Speed Sense LossCheck quad leads fully seated in connector to control, control plugs fully seated, field windings, proper field resistance reading, open to ground, brush condition and contact, grounded or shorted quad windings
48Control Card Field Voltage SenseCheck verify fault
58High Exhaust TempCheck broken or loose switch leads, exhaust temperature switch S5, raw water flow
61Emergency ShutdownCheck customer input connections, K5 relay operation (if equipped)
CODE NO. 15UNDERFREQUENCY—Engine governor unable to maintain rated frequency1. Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. 2. Check the fuel tank and fill as necessary. (Note: The arrangement of pickup tubes in the fuel supply tank probably is such that the genset will run out of fuel before the propulsion engines.) 3. Remove any blockage in the combustion air inlet (front grille) or exhaust system. 4. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 5. Drain and/or replace the fuel filter (Page 16) and prime the fuel system (Page 8). 6. Drain and/or replace fuel supply system filters and prime the fuel system (Page 8).
CODE NO. 17OVER-PRIME—Prime mode exceed 5 minutesCheck for and remove any object that may be holding either control switch (remote or local) in the prime position.
CODE NO. 22GOVERNOR OVERLOAD—Maximum allowable time at full-duty cycle was exceeded1. Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. 2. Check the fuel tank and fill as necessary. (Note: The arrangement of pickup tubes in the fuel supply tank probably is such that the genset will run out of fuel before the propulsion engines.) 3. Remove any blockage in the combustion air inlet (front grille) or exhaust system. 4. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 5. Drain and/or replace the fuel filter (Page 16) and prime the fuel system (Page 8). 6. Drain and/or replace fuel supply system filters and prime the fuel system (Page 8).
CODE NO. 23FAULTY OIL PRESSURE SENDER—Controller sensed grounded senderSee an authorized Onan dealer.
CODE NO. 24FAULTY TEMPERATURE SENDER—Controller sensed open senderSee an authorized Onan dealer.
CODE NO. 27LOSS OF VOLTAGE SENSE—Controller unable to sense output voltageSee an authorized Onan dealer.
CODE NO. 29HIGH BATTERY VOLTAGE—Battery system at more than 19.2 volts if 12 VDC system, or 38.4 volts if 24 volt system1. Check battery bank connections and reconnect if necessary to supply 12 volts or 24 volts, as appropriate. 2. Select a lower battery boost charge rate.
CODE NO. 35CONTROL CARD FAILURE—Microprocessor EEPROM error during self-testSee an authorized Onan dealer.
CODE NO. 36ENGINE STOPPED—Engine stopped without command by controller1. Open any closed fuel supply valves. 2. Check the fuel tank and fill as necessary. (Note: The arrangement of pickup tubes in the fuel supply tank probably is such that the genset will run out of fuel before the propulsion engines.) 3. Check for mechanical damage and service as necessary. 4. Remove any blockage in the combustion air inlet (front grille) or exhaust system. 5. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 6. Drain and/or replace the fuel filter (Page 16) and prime the fuel system (Page 8). 7. Drain and/or replace fuel supply system filters and prime the fuel system (Page 8).
CODE NO. 37INVALID GENSET CONFIGURATION—Controller cannot determine genset operating parametersSee an authorized Onan dealer.
CODE NO. 38FIELD OVERLOAD—High field voltage induced by high rotor temperature or low power factor loads1. Remove blockages to generator air flow at the front inlet grill and right side, if enclosed. 2. Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. 3. Have air conditioners and other appliances checked for proper operation. (A locked compressor rotor can cause very low power factor.)
CODE NO. 41GROUNDED ROTOR—F+ groundedSee an authorized Onan dealer.
CODE NO. 42PROCESSOR FAILURE—Microprocessor ROM error during self-testSee an authorized Onan dealer.
CODE NO. 43PROCESSOR FAILURE—Microprocessor RAM error during self-testSee an authorized Onan dealer.
CODE NO. 48PROCESSOR FAILURE—Controller unable to sense field voltageSee an authorized Onan dealer.
CODE NO. 58HIGH EXHAUST TEMPERATURE—Exhaust temperature exceeded design limits1. Check for and reconnect or replace any disconnected or leaking raw water hoses (Page 19). 2. Check for a and replace a worn raw water impeller(Page 23)
1HIGH ENGINE TEMPERATURE1. Add coolant as necessary and repair leaks (Page 18). 2. Replace the engine thermostat, which might not be opening fully (Page 21). 3. Clean the raw water tubes in the heat exchanger, which might be clogged with scale (Page 22). 4. Flush the coolant system to remove coolant passage fouling (Page 18).
3SERVICE CHECKCheck the second-level shutdown code by pressing STOP once. The second-level shutdown code will have two-digits. The shutdowns are listed below in numerical order.
4OVERCRANK1. Check the fuel tank and fill as necessary. (Note: The arrangement of pickup tubes in the fuel supply tank probably is such that the genset will run out of fuel before the propulsion engines.) 2. Open any closed fuel valves. 3. Remove any blockage in the combustion air inlet (front grille) or exhaust system. 4. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 5. Drain and/or replace the fuel filter (Page 16) and prime the fuel system (Page 8). 6. Drain and/or replace fuel supply system filters and prime the fuel system (Page 8).
7LOSS OF RAW WATER FLOW1. Open the sea cock. 2. Close the sea cock and clean the sea water strainer. If the strainer is above the water line, fill it with water to assist priming. Secure the strainer cover and reopen the sea cock. 3. Reconnect or replace any disconnected or leaking raw water hoses (Page 19). 4. Remove any blockage from the strainer on the through-hull fitting on the bottom side of the hull. 5. Replace the raw water impeller (Page 23).
12OVERVOLTAGESee an authorized Onan dealer.
13UNDERVOLTAGEReduce the number of connected appliances, especially when air conditioners and battery chargers are running.
1 or 2 digit codeStatus light on the generator will repeatedly blink a 1 or 2 digit code after a protective shutdown
high engine coolant temperatureCommon fault such as high engine coolant temperature
high exhaust temperatureCommon fault such as high exhaust temperature
low oil pressureCommon fault such as low oil pressure
1HIGH ENGINE TEMPERATURE—CODE NO. 1 (Engine coolant temperature exceed design limit)1. Check for and clean a blocked sea water strainer. If above the water line, fill the strainer with water to assist priming. 2. Check engine coolant level and add coolant as necessary. 3. Check for kinked or leaking hoses and reconnect, reroute or replace. 4. Check the V-belt that drives the coolant pump and service as necessary 5. Inspect the siphon break (if provided) for proper operation. 6. Check for a worn raw water impeller and replace as necessary 7. Clean the heat exchanger
4OVERCRANK—CODE NO. 4 (Cranking time exceeded 20 to 60 seconds, depending on ambient temperature)1. Check fuel level and refill as necessary. 2. Open any closed fuel supply and return valves. 3. Prime the engine fuel system for at least 30 seconds 4. Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables 5. Replace the fuel filters and reprime 6. Check all fuel fittings for fuel and air leaks, tighten as necessary and reprime. 7. Change the engine oil to oil of the proper viscosity for the ambient temperature
14HIGH AC FREQUENCY—CODE NO. 14 (After the starter was engaged Frequency jumped to more than 70 Hz for 40 milliseconds or to more than 2% over nominal for 6 seconds)1. Check for a tripped genset circuit breaker, reset it if necessary, and run with fewer connected loads. 2. Check all fuel fittings for fuel and air leaks and tighten as necessary and reprime.
15LOW AC FREQUENCY—CODE NO. 15 (During normal operation Frequency fell to less than 90% of nominal for more than 8 seconds)Push the genset line circuit breaker OFF. If the genset now runs, reduce the number of loads.
3Service faultPress Stop once to cause the two-digit shutdown code to blink
4Shutdown due to a failure to start within the time allowed for cranking
7Shutdown due to a loss of raw water flow for engine and exhaust cooling

Symptoms & remedies

SymptomCauseRemedy
NO RESPONSE AT OPERATOR PANEL OR CONTROL SWITCHFaulty switch, poor or missing connections, dead battery1. Push the Emergency Stop Breaker ON if tripped. 2. Try the Operator Panel or control switch on the generator set (local) if there is no response at a remote Operator Panel or control switch, and vice versa.. 3. If none of the Operator Panels or control switches works, service as necessary by cleaning and tightening battery connections, recharging or replacing the battery or replacing damaged battery cables (p. 4-3).
THE STARTER ENGAGES AND DISENGAGESLow cranking voltage1. Push the generator set line circuit breaker OFF. 2. Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables (p. 4-3).
THE STARTING BATTERIES DO NOT MAINTAIN A CHARGEMarginal battery, battery connections or charging system1. Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables (p. 4-3). 2. Check for and disconnect parasitic battery loads.
NO AC POWER WHEN GENERATOR SET IS RUNNINGA Circuit Breaker is OFF
The Digital Display will display a description of the Fault, the numeric Fault code and the accumulated number of hours of generator set operating time when the Fault occurredRefer to TABLE 5-1. TROUBLESHOOTING GENERATOR SET FAULTS to diagnose and correct the problem.
The Digital Display will display the fault indefinitely.Touch any button to clear the fault. The Digital Display will turn off in 5 minutes after the fault has been cleared.
Engine coolant temperature exceeds design limitCheck for and clean a blocked sea water strainer. If above the water line, fill the strainer with water to assist priming. Check engine coolant level and add coolant as necessary. Check for kinked or leaking hoses and reconnect, reroute or replace. Check the V-belt that drives the coolant pump and service as necessary (p. 4-13). Inspect the siphon break for proper operation (p. 4-8). Check for a worn raw water impeller and replace as necessary (p. 4-12). Clean the heat exchanger (p. 4-8). Check the bottom of the hull for any blockage at the through-hull fitting. Replace the coolant thermostat, which might not be opening fully (p. 4-14). Drain and clean the coolant system to remove coolant passage fouling (Page 4-7).
Low oil pressureCheck the engine oil level and add or drain oil as necessary (p. 4-3). Repair any oil leaks.
A fault with a 2-Digit Fault Code Number occurredCheck the 2-Digit fault code by Pushing and Releasing Stop. The 2-Digit fault will be one of the following in this table. (Does not apply to Digital Display.)
The generator set does not start after several tries.
The genset does not start after several tries.
Cranking will discontinue in 20 to 60 seconds, depending on engine temperature.See Troubleshooting (Section 9) if the genset does not start after several tries.
The e-Series Digital Display and/or control switch status lamp will indicate the numeric fault code.See Troubleshooting (Section 9).
NO RESPONSE AT DIGITAL DISPLAY OR CONTROL SWITCH (Faulty switch, poor or missing connections, dead battery)1. Push the Emergency Stop and/or DC Circuit Breaker ON if tripped. 2. Try the Digital Display or control switch on the generator set (local) if there is no response at a remote Display or control switch, and vice versa.. 3. If none of the Displays or control switches works, service as necessary by cleaning and tightening battery connections, recharging or replacing the battery or replacing damaged battery cables (p. 4-2).
THE STARTER ENGAGES AND DISENGAGES (Low cranking voltage)1. De-energize the PTO clutch, if so equipped. 2. Service as necessary by cleaning and tightening battery connections, recharging or replacing the battery or replacing damaged battery cables (p. 4-2).
THE STARTING BATTERIES DO NOT MAINTAIN A CHARGE (Marginal battery, battery connections or charging system)1. Service as necessary by cleaning and tightening battery connections, recharging or replacing the battery or replacing damaged battery cables (p. 4-2). 2. Check the V-belt that drives the charging alternator and service as necessary (p. 4-13). 3. Check for and disconnect parasitic battery loads.
NO AC POWER WHEN GENERATOR SET IS RUNNING (A Circuit Breaker is OFF, tripped or malfunctioning or the generator is not connected properly)1. Reset, turn ON or repair the generator set circuit breaker, as necessary. 2. Reset, turn ON or repair the AC power supply to the generator set.
NO AC POWER WHEN GENSET IS RUNNING (A Circuit Breaker is OFF, tripped or malfunctioning or the generator is not connected properly)Reset, turn ON or repair the genset circuit breaker, as necessary. Reset, turn ON or repair any other circuit breaker in the AC power supply system, as necessary.
Output voltage-Check: -Field windings -Proper field resistance reading, open to ground -Brush condition and contact -Grounded or shorted main windings -Perform checks in step 01
The genset fails to startCranking will discontinue in 20 to 60 seconds, depending on how cold the engine is, and the amber status lamp will blink Shutdown Code No. 4 (Page 7-5). See Troubleshooting (Page 7-1) if the genset does not start after two or three tries.
The genset shuts downSee Troubleshooting (Page 7-1).
The genset shuts down.See Troubleshooting (Section 9).
STARTER ENGAGES-DISENGAGES(Battery voltage dips below 6 volts while cranking—low battery charge, poor connections, long cables)1. Clean and tighten the positive (+) and negative (- ) battery cable connections at the battery and gen-set (Page 17). 2. Recharge or replace the battery. Refer to the battery manufacturer’s recommendations. 3. Increase battery cable size or run parallel cables.
RUN-DOWN STARTING BATTERY(Marginal battery, connections, or charging system or, parasitic loads)1. Clean and tighten the positive (+) and negative (- ) battery cable connections at the battery and gen-set (Page 17). 2. Recharge or replace the battery. Refer to the battery manufacturer’s recommendations.
ENGINE CRANKS, STARTS, ACCELERATES, BUT STOPS WHEN SWITCH LET GO(Open field or open or grounded quadrature circuit)Corrective Action: See an authorized Onan dealer.
NO LIGHTS, NO RESPONSE(Poor connections, faulty wiring or dead battery)1. Try the genset Control Switch if the remote Control Switch does not work, and vice versa. 2. Clean and tighten the positive (+) and negative (- ) battery cable connections at the battery and gen-set (Page 17). 3. Recharge or replace the battery. Refer to the battery manufacturer’s recommendations.
Circuit breaker OFFIf the genset now runs, reduce the number of loads, especially those with high motor starting loads such as air conditioners. Check fuel level and fill as necessary. Prime the engine fuel system for at least 30 seconds (p. 3-3). Check all fuel fittings for fuel and air leaks, tighten as necessary and reprime. Replace the fuel filters and reprime (p. 4-5).
Engine keeps shutting down (Code No. 1)Heat exchanger tubes are dirtyClean the raw water tubes
Engine gauge indicates abnormally high engine temperaturesHeat exchanger tubes are dirtyClean the raw water tubes

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.

Common questions

Cummins/Onan MDKB: NO RESPONSE AT OPERATOR PANEL OR CONTROL SWITCH — what causes it?

Documented causes: Faulty switch, poor or missing connections, dead battery. See the table for the matching fixes.

Cummins/Onan MDKB: THE STARTER ENGAGES AND DISENGAGES — what causes it?

Documented causes: Low cranking voltage. See the table for the matching fixes.

Cummins/Onan MDKB: THE STARTING BATTERIES DO NOT MAINTAIN A CHARGE — what causes it?

Documented causes: Marginal battery, battery connections or charging system. See the table for the matching fixes.