Cummins ISC CM2150 (2007-09) Fault Code: 688 PID: 98 SPN: 98 FMI: 0 Engine Oil Level – Data Valid but Above Normal Operational Range – Most Severe Level. High oil level has been detected by the oil level sensor.

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM.

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:

1)The engine may have been overfilled with oil during the most recent oil change.
2)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.
3)The cooling system may be leaking into the lube oil system. Check for coolant in the oil.

Possible repairs:

1)Correct the engine lubricating oil level condition.