Engine Oil Level — Data Valid But Above Normal Operational Range — Most Severe Level
|Fault Code: 688
Engine Oil Level — Data Valid But Above Normal Operational Range —
Possible low power, excessive smoke, oil dilution, contamination, or severe engine damage. The engine may derate.
Circuit: Engine Oil Level Sensor.
An algorithm in the ECM calibration monitors engine oil level while the ECM is keyed on and no engine speed is detected. If the engine oil level exceeds a certain threshold, the ECM will activate Fault 688.
The engine oil level sensor is located on the engine oil dipstick, on the air intake side of the engine. 100-002 (Engine Diagrams) in section E for further details on dipstick location.
Fault code 688 indicates that the oil level in the engine is much higher than the recommended oil level.
Other causes of fault code 688 may include:
- The engine may have been overfilled with oil during the most recent oil change
- The fuel system may be leaking into the lube oil system. (Check for fuel system faults or use fluorescent fuel system dye to identify leaks)
- The cooling system may be leaking into the lube oil system. (Check for coolant in the oil).
On-Board Diagnostic (OBD) Information:
- The ECM illuminates the appropriate amber or red fault lamp when the diagnostic runs and fails
- The ECM turns off the appropriate fault lamp when the diagnostic runs and passes.