Cummins/Onan MDJA troubleshooting: 2 fault codes and 95 symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan MDJA — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning |
|---|---|
| e008 | No specific name provided for e008 |
| 10 | Overload |
| Symptom | Cause | Remedy |
|---|---|---|
| Engine will not crank | Battery discharged | Recharge |
| Engine will not crank | Loose connections | Tighten connections |
| Engine will not crank | Defective starting circuit | Repair or replace as necessary |
| Engine will not crank | Defective starting motor on revolving field generator | Repair or replace as necessary |
| Engine will not crank | Defective switch | Replace |
| Engine will not crank | Poor generator brush contact on revolving armature generator | Replace brush. Refinish surface |
| Engine cranks too stiffly | Too heavy oil in crankcase | Drain, refill with lighter oil |
| Engine cranks too stiffly | Engine stuck | Disassemble and repair |
| Engine cranks too stiffly | Load connected | Disconnect |
| Engine cranks too stiffly | Decompression release (on 1 cyl diesel) at running position | Place at start position |
| Engine will not start when cranked | Air in fuel system | Bleed the fuel system |
| Engine will not start when cranked | Lack of fuel or faulty injection caused by dirty fuel | Refill the tank. Check the fuel system. Clean, adjust, or replace parts necessary |
| Engine will not start when cranked | Clogged fuel filter | Clean strainer (primary). Install new cartridge (secondary) |
| Engine will not start when cranked | Poor compression | Tighten cylinder head. Replace head gasket. If still not corrected, grind the valves. Replace piston rings, if necessary |
| Engine will not start when cranked | Wrong timing | Check injection pump timing |
| Engine stops when start switch is released | Centrifugal switch remained open | Clean and adjust |
| Engine runs but voltage does not build up | Poor brush contact | See that brushes seat well, are free in their holders, are not worn too short, and have good spring tension |
| Engine runs but voltage does not build up | Open circuit, short circuit, or ground in generator | Replace parts necessary |
| Engine runs but voltage does not build up | Residual magnetism lost | Spec B exciters - press residual reset button; spec A exciters — consult dealer |
| Engine runs but voltage does not build up | Dirty relay contacts in 02SX Magneciter | Clean with paper |
| Engine runs but voltage does not build up | Faulty Magneciter | Trouble shoot Magneciter |
| Excessive oil consumption, light blue smoky exhaust | Poor compression, usually due to worn piston, rings, or cylinder | Refinish cylinder. Install oversize piston and rings |
| Excessive oil consumption, light blue smoky exhaust | Oil leaks from oil base or connections. This does not cause smoky exhaust | Replace gaskets. Tighten screws and connection. Check breather valve |
| Excessive oil consumption, light blue smoky exhaust | Oil too light or diluted | Drain, refill with correct oil |
| Excessive oil consumption, light blue smoky exhaust | Worn engine | Repair as necessary |
| Excessive oil consumption, light blue smoky exhaust | Worn intake valve guide or valve stem | Replace |
| Excessive oil consumption, light blue smoky exhaust | Engine misfiring | Refer to symptoms of engine misfiring |
| Excessive oil consumption, light blue smoky exhaust | Too much oil | Drain excess oil |
| Black, smoky exhaust, excessive fuel consumption, possible low power under heavy load | Generator overloaded. Black smoky exhaust normal condition with overload | Reduce load to within rated capacity. If smoky condition continues, stop unit and investigate |
| Black, smoky exhaust, excessive fuel consumption, possible low power under heavy load | Poor compression | Tighten cylinder head, grind or replace valves, replace piston rings as needed |
| Black, smoky exhaust, excessive fuel consumption, possible low power under heavy load | Poor grade or dirty fuel | Use only clean, recommended fuel |
| Black, smoky exhaust, excessive fuel consumption, possible low power under heavy load | Injection pump or nozzle not operating properly | Clean nozzle. If necessary, install new nozzle or injection pump |
| Black, smoky exhaust, excessive fuel consumption, possible low power under heavy load | Faulty injection timing | Check injection pump timing |
| Black, smoky exhaust, excessive fuel consumption, possible low power under heavy load | Dirty air cleaner | Clean |
| Engine stops unexpectedly | Fuel tank empty | Refill |
| Engine stops unexpectedly | Safety switch operated (where used) | Correct the overheating or the lubrication failure. Press reset switch. Replace unless one of the next two remedies permanently corrects the trouble |
| Dull metallic thud. If not bad, may disappear after few minutes operation. If bad, increases with load | Loose crankshaft bearing | Replace |
| Dull metallic thud. If not bad, may disappear after few minutes operation. If bad, increases with load | Low oil supply | Add oil |
| Dull metallic thud. If not bad, may disappear after few minutes operation. If bad, increases with load | Oil badly diluted | Change oil |
| Sharp metallic thud, especially when cold engine first started | Valve clearance too great | Adjust. Replace faulty valve system |
| Sharp metallic thud, especially when cold engine first started | Broken valve spring | Install new spring |
| Tapping sound | Loose piston | If noise only slight and disappears when engine warms up, no immediate attention needed. Otherwise replace worn parts |
| Hollow clicking sound with cool engine under load | Loose connecting rod bearing | Adjust or replace |
| Light pounding knock (knock from firing of fuel is normal) | Low oil supply | Add oil |
| Light pounding knock (knock from firing of fuel is normal) | Oil badly diluted | Change oil |
| Engine races | Too much fuel injected. STOP UNIT AT ONCE! | Check governor performance and linkage condition |
| Engine misfires | Faulty injection | Clean fuel system. Use clean recommended fuel |
| Engine misfires | Low compression | Tighten cylinder head. Service valves and piston rings as needed |
| Low oil pressure | Defective gauge | Replace |
| Low oil pressure | Oil too light or diluted from leaking fuel pump diaphragm | Drain. Refill with proper oil. Repair or replace transfer pump |
| Low oil pressure | Oil too low | Add oil |
| Low oil pressure | Oil relief valve not seating | Clean. Replace if needed |
| Low oil pressure | Badly worn bearings | Replace |
| Low oil pressure | Sludge on oil cup screen | Clean screen and oil sump |
| Low oil pressure | Badly worn oil pump | Replace |
| High oil pressure | Defective gauge | Replace |
| High oil pressure | Oil too heavy grade | Drain. Refill |
| High oil pressure | Clogged oil passages | Clean all lines and passages |
| High oil pressure | Oil relief valve stuck | Clean by-pass. Replace if needed |
| Engine overheating | Poor coolant circulation | Maintain supply |
| Engine overheating | Improper lubrication | See Low Oil Pressure |
| Engine overheating | Wrong injection timing | Retime |
| Engine overheating | Generator overloaded | Reduce load |
| Voltage low at far end of line but normal near power plant | Too small line wire for load and distance | Install larger or extra wires or reduce load |
| Electric motor runs too slowly and overheats at far end of line but OK if used near power unit | Too small line wire for load and distance | Install larger or extra wires or reduce load |
| Voltage unsteady but engine not misfiring | Speed too low | Adjust governor to correct speed |
| Voltage unsteady but engine not misfiring | Poor brush contact (or poor commutation on revolving armature models) | See that brushes seat well on commutator, are free in their holders, are not worn too short, and have good spring tension |
| Voltage unsteady but engine not misfiring | Loose connections | Tighten connections |
| Voltage unsteady but engine not misfiring | Fluctuating load | Correct any abnormal load condition causing trouble |
| Noisy and excessive arcing of brushes (revolving armature model) | Rough commutator | Turn down. Undercut mica between bars |
| Noisy and excessive arcing of brushes (revolving armature model) | Dirty commutator | Clean |
| Noisy and excessive arcing of brushes (revolving armature model) | Brushes not seating properly | Sand to a good seat |
| Noisy and excessive arcing of brushes (revolving armature model) | Open circuit in armature | Replace |
| Noisy and excessive arcing of brushes (revolving armature model) | Brush rig out of position | Line up properly |
| Generator overheating (approximately 160°F. higher than ambient) | Brush rig out of position (Revolving armature generator) | Adjust |
| Generator overheating (approximately 160°F. higher than ambient) | Overloaded | Reduce load |
| Voltage drops under heavy load | Engine lacks power | See remedies for engine misfires |
| Voltage drops under heavy load | Poor compression | Tighten cylinder head and spark plug. If still not corrected, grind the valves. Replace piston rings, if necessary |
| Voltage drops under heavy load | Faulty injection | Check the fuel system. Clean, adjust or replace parts necessary |
| Voltage drops under heavy load | Dirty air cleaner | Clean |
| Voltage drops under heavy load | Restricted exhaust line | Clean or increase the size |
| Engine does not start | Little or no exhaust smoke | Prime fuel system as shown |
| Engine does not start | Little or no fuel flow from return line | Use alternate bleeding method as stated in manual |
| Engine does not start | Fuel flow from return line, still no smoke | Use alternate bleeding method as stated in manual |
| Engine does not start | Fuel tank empty | Check fuel supply system |
| Engine does not start | Shutoff valves closed | Check fuel supply system |
| Engine does not start | Fuel lines kinked | Check fuel supply system |
| Engine does not start | Loose connections | Check fuel supply system |
| Engine does not start | Clogged fuel filters | Check fuel supply system |
| Engine does not start | Transfer pump may be defective (fuel does not spurt out from return line when cranking) | Check transfer pump: crank engine and observe fuel flow from return line |
| Engine does not start | Preheat system not functioning (heater element does not glow red within 30 seconds) | Check for clean, tight connections |
| Engine does not start | Decompression mechanism out of adjustment | Check adjustment as outlined in manual |
| Engine does not start | Blue-white exhaust smoke: engine is getting fuel (fuel flows steadily from fuel return line) | Repeat starting procedures, including preheat; if it still does not start, contact authorized Onan service representative |
| Engine does not start at temperatures below 32°F (0°C) | Incorrect fuel or oil viscosity; batteries not fully charged | Use Number 1 diesel fuel; use correct viscosity oil; keep batteries fully charged; do not use ether starting aid |
| Set does not stop | Stop circuit fails | Close fuel valve |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Little or no exhaust smoke; Little or no fuel flow from return line; Fuel flow from return line, still no smoke; Fuel tank empty. See the table for the matching fixes.
Documented causes: Poor compression, usually due to worn piston, rings, or cylinder; Oil leaks from oil base or connections. This does not cause smoky exhaust; Oil too light or diluted; Worn engine. See the table for the matching fixes.
Documented causes: Defective gauge; Oil too light or diluted from leaking fuel pump diaphragm; Oil too low; Oil relief valve not seating. See the table for the matching fixes.