The Cummins/Onan MDKAU is a 0.4 L 2-cylinder naturally aspirated engine rated at 3600 rpm. It holds 2.1 L (0.6 gal) of oil and 2.1 L (0.6 gal) of coolant.
Also known as: Cummins MDKAU
| Oil capacity | 2.1 L |
|---|---|
| Coolant capacity | 2.1 L |
| Displacement | 0.4 L |
| Cylinders | 2 |
| Aspiration | naturally aspirated |
| Rated speed | 3600 rpm |
No generator set in our catalog cites this exact engine designation yet; its specifications and fault codes are documented here.
How to read your Cummins/Onan engine serial & model number →
| Code | Meaning | Remedy |
|---|---|---|
| 15 | UNDERFREQUENCY—CODE NO. 15 (Engine governor unable to maintain rated frequency) | 1. 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 (lower rear of left end of genset). 4. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 5. Drain the fuel filter of water and sediment (Page 15) and prime the fuel system (Page 8). 6. Drain and/or replace fuel supply system filters and prime the fuel system (Page 8). |
| 17 | OVER-PRIME—CODE NO. 17 (Prime mode exceed 5 minutes) | Check for and remove any object that may be holding either control switch (remote or local) in the prime position. |
| 19 | GOVERNOR ACTUATOR—CODE NO. 19 (Controller sensed an open or short circuit in actuator circuit) | See an authorized Onan dealer. |
| 22 | GOVERNOR OVERLOAD—CODE NO. 22 (Maximum allowable time at full-duty cycle was exceeded) | 1. 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 (lower rear of left end of genset). 4. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 5. Drain the fuel filter of water and sediment (Page 15) and prime the fuel system (Page 8). 6. Drain and/or replace fuel supply system filters and prime the fuel system (Page 8). |
| 23 | FAULTY OIL PRESSURE SENDER—CODE NO. 23 (Controller sensed shorted or grounded sender) | See an authorized Onan dealer. |
| 24 | FAULTY TEMPERATURE SENDER—CODE NO. 24 (Controller sensed open or grounded sender) | See an authorized Onan dealer. |
| 27 | LOSS OF VOLTAGE SENSE—CODE NO. 27 (Controller unable to sense output voltage) | See an authorized Onan dealer. |
| 29 | HIGH BATTERY VOLTAGE—CODE NO. 29 (Battery system at more than 19.2 volts) | 1. Check battery bank connections and reconnect if necessary to supply 12 volts. 2. Select a lower battery boost charge rate. |
| 35 | CONTROL CARD FAILURE—CODE NO. 35 (Microprocessor EEPROM error during self-test) | See an authorized Onan dealer. |
| 36 | ENGINE STOPPED—CODE NO. 36 (Engine stopped without command by controller) | 1. 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 (lower rear of left end of genset). 5. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 6. Drain the fuel filter of water and sediment (Page 15) and prime the fuel system (Page 8). 7. Drain and/or replace fuel supply system filters and prime the fuel system (Page 8). |
| 37 | INVALID GENSET CONFIGURATION—CODE NO. 37 (Controller cannot determine genset operating parameters) | See an authorized Onan dealer. |
| 38 | FIELD OVERLOAD—CODE NO. 38 (High field voltage induced by high rotor temperature or low power factor loads) | 1. Remove blockages to generator air flow at the left side and front of genset. 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.) |
| 41 | GROUNDED ROTOR—CODE NO. 41 (F+ grounded) | See an authorized Onan dealer. |
| 42 | PROCESSOR FAULT—CODE NO. 42 (Microprocessor ROM error during self-test) | See an authorized Onan dealer. |
| 43 | PROCESSOR FAULT—CODE NO. 43 (Microprocessor RAM error during self-test) | See an authorized Onan dealer. |
| 48 | PROCESSOR FAILURE—CODE NO. 48 (Controller unable to sense field voltage) | See an authorized Onan dealer. |
| CODE NO. 1 | HIGH ENGINE TEMPERATURE—First-level shutdown—Engine coolant temperature exceed design limit | 1. Add coolant as necessary and repair leaks (Page 17). 2. Replace the engine thermostat, which might not be opening fully (Page 19). 3. Clean the raw water tubes in the heat exchanger, which might be clogged with scale (Page 22). |
| CODE NO. 2 | LOW OIL PRESSURE—First-level shutdown—Low oil pressure | 1. Add engine oil as necessary (Page 13). 2. Drain excess oil (above top bead on dipstick). |
| CODE NO. 3 | SERVICE CHECK—First-level shutdown—Indicates presence of second-level shutdown | Check 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. |
| CODE NO. 4 | OVERCRANK—First-level shutdown—Cranking exceeded 20 to 60 seconds [temperature dependent] without start | 1. 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 (lower rear of left side) or exhaust system. 4. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 5. Drain the fuel filter of water and sediment (Page 15) 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. 7 | LOSS OF RAW WATER FLOW—First-level shutdown—Low raw water pressure in heat exchanger | 1. Open the sea cock all the way. 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 17). 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 20). |
| CODE NO. 12 | OVERVOLTAGE—Controller unable to maintain rated voltage | See an authorized Onan dealer. |
| CODE NO. 13 | UNDERVOLTAGE—Controller unable to maintain rated voltage | Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. |
| CODE NO. 14 | OVERFREQUENCY—Engine governor unable to maintain rated frequency | See an authorized Onan dealer. |
| 14 | Overfrequency | Check engine speed, loads, governor actuator operation, fuel supply, control plugs fully seated, quad leads fully seated in connector to control, quad winding resistance |
| 15 | Underfrequency | Check engine speed, loads, governor actuator operation, fuel supply, control plugs fully seated, quad leads fully seated in connector to control, quad winding resistance |
| 17 | Overprime | Check battery voltage, fuel supply, start/stop switch (local and remote), shorted wiring |
| 22 | Actuator Overload | Check 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 |
| 23 | Faulty Oil Pressure Sender | Check oil level, grounded or shorted sender lead, sender resistance (low); Perform checks in step 01; Check oil pressure (mechanical) |
| 24 | Faulty Temperature Sender | Check coolant level, open or loose sender lead, sender resistance (high); Perform checks in step 01; Check coolant temperature |
| 27 | Loss of Voltage Sense | Check 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 |
| 29 | High Battery Voltage | Check battery voltage, battery connections, battery charge rate |
| 35 | Control Card EE Checksum | Check verify fault |
| 36 | Engine Stopped | Check 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 |
| 37 | Invalid Set Configuration | Check configuration number |
| 38 | Field Overflow | Check 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 |
| 41 | Grounded Rotor | Check fuel supply, field windings, proper field resistance reading, open to ground, brush condition and contact |
| 42 | Control Card ROM | Check verify fault |
| 43 | Control Card RAM | Check verify fault |
| 45 | Speed Sense Loss | Check 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 |
| 48 | Control Card Field Voltage Sense | Check verify fault |
| 58 | High Exhaust Temp | Check broken or loose switch leads, exhaust temperature switch S5, raw water flow |
| 61 | Emergency Shutdown | Check customer input connections, K5 relay operation (if equipped) |
| Symptom | Remedy |
|---|---|
| NO POWER—GENSET RUNNING, RUN LAMP ON (Line circuit breaker OFF or tripped) | 1. Turn on or reset the line circuit breaker on the genset (Page 7). 2. Turn on or reset the line circuit breakers on the main distribution panel in the boat. |
| STARTER ENGAGES-DISENGAGES (Cranking voltage dips below 6 volts—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 16). 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 16). 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) | 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 16). 3. Recharge or replace the battery. Refer to the battery manufacturer’s recommendations. |
| 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 |
| Burning out the starter or flooding the engine (exhaust flow during cranking is too low to expel water from the exhaust system). | Find out why the genset does not start and make necessary repairs. |
Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.
| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Fuel filter | Fuel filter change | — | 800 hr | ||
| Oil filter | Oil filter replacement | — | 500 hr | ||
| Battery | Battery check and maintenance | — | 100 hr | ||
| Coolant | Coolant, pressure cap, and thermostat replacement | 2.1 liter | — | 2000 hr | |
| Oil | Engine oil with proper viscosity | 2.1 liter | — | 500 hr |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
Step-by-step procedures compiled from the Cummins/Onan service manual for this engine.
The Cummins/Onan MDKAU engine has an oil capacity of 2.1 liters.
The Cummins/Onan MDKAU has a displacement of 0.4 liters with 2 cylinders.
The Cummins/Onan MDKAU oil change interval is every 500 hours.