Cummins/Onan QSx15 troubleshooting: 21 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan QSx15 — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning |
|---|---|
| TS-56 | White — Excessive.... |
| 18-57 | Turbocharger Boost Pressure Low.... |
| TS-58 | Turbocharger Leaks Engine Oil or Fuel... |
| 235 | Fault Code 235: Blink 1 Blinks 3 Blinks 31 ‘Bcke 5 sBitnks 7 Blink |
| OS | Overspeed |
| LOP | Low Oil Pressure |
| HET | High Engine Temperature |
| Fault 1 | High Engine Temperature Shutdown |
| V2 | Fault Code V2 |
| Symptom | Cause | Remedy |
|---|---|---|
| The yellow lamp is illuminated. | The engine is in need of repair at the first available opportunity. | |
| The warning light flashes for 30 seconds at key-on. | Maintenance required (if maintenance monitor is enabled) or Water-in-fuel is detected. | Replace the secondary fuel filter if water is drained from the primary water-separating fuel filter. |
| Engine overspeed during cranking. | Do not depress the accelerator pedal or move the accelerator lever from the idle position while cranking the engine. | |
| Starting motor damage. | Do not engage the starting motor for more than 30 seconds and wait 2 minutes between each attempt to start (electrical starting motors only). | |
| Engine does not start after three attempts. | Check the fuel supply system. Absence of blue or white exhaust smoke during cranking indicates no fuel is being delivered. | |
| Low oil pressure within 15 seconds after starting. | Shut off the engine immediately to reduce the possibility of engine damage. The low oil pressure troubleshooting procedure is located in Troubleshooting Symptoms (Section TS). | |
| Engine overheating. | Reduce the power output of the engine by releasing the accelerator pedal or shifting the transmission to a lower gear, or both, until the temperature returns to the normal operating range. If the engine temperature does not return to normal, shut off the engine and refer to Troubleshooting Symptoms (Section TS) or contact a Cummins Authorized Repair Location. | |
| Engine misfires, vibration, unusual noises, sudden changes in operating temperatures or pressures, excessive smoke, loss of power, increased oil consumption, increased fuel consumption, or leaks. | Look and listen for these changes as they can indicate service or engine repair is needed. | |
| Lubricating oil drain interval is excessive | Verify the correct lubricating oil drain interval. Refer to Section 2. | |
| No Fault Codes Recorded | Turn the vehicle keyswitch to the ON position. If no active fault codes are recorded, all three lights will come on and stay on. | |
| Active fault codes are recorded, all three lights will come on momentarily. The amber (warning) and red (stop) lights will begin to flash the code of the recorded fault. | The fault code will flash in the following sequence: First, the amber (warning) lamp will flash. Then there will be a short 1-second pause when both the amber and red lights are off. Then the numbers of the recorded fault code will flash in red, There will be a 1-second pause between each number. When the number has stopped flashing, an amber light will appear again. The number will repeat in the same sequence. | |
| The lights wili continue to flash the same fault code until the system has advanced to the next active fault code. | To go to the second fault code, move the idle-speed adjust switch to "+", then release it. You can also go back to the previous fault code by moving the switch to "-", then releasing it. To check the third or fourth fault code, move the switch to "+", then release it when all active fault codes have been viewed, Moving the switch to "+" will go back to the first fault code. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: The engine is in need of repair at the first available opportunity.. See the table for the matching fixes.
Documented causes: Maintenance required (if maintenance monitor is enabled) or Water-in-fuel is detected.. See the table for the matching fixes.