Cummins ISX CM870 (2003-06) Fault Code: 234 PID: P190 SPN: 190 FMI: 0/0 Engine Crankshaft Speed/Position – Data Valid But Above Normal Operating Range – Most Severe Level. Engine speed signal indicates engine speed above engine protection limit.

Possible causes:

1)External fuel sources drawn into the intake air passage
2)Reverse powering (motoring) of the engine
3)Tampering of the engine speed/position sensors.
Inspect the intake manifold for sources of flammable vapors. Check the turbocharger seals to verify there are no oil leaks. Inspect the engine speed/position sensors for damage or tampering.

Possible repairs:

1)Replace the ECM.