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For 1990-2009 cars only

DTC U1000 Stored History Or Current - keywords PI01116 class crank communication inoperative LA1 LG8 level missing no oil sensor start system

Subject:DTC U1000 Stored History Or Current

Models:2003-2005 Chevrolet Malibu (Classic)
2003-2005 Oldsmobile Alero
2003-2005 Pontiac Grand-am



PIC4129A was created to inform Technicians on the U1000 if in the PCM only. Please discard PIC4129.


The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

The diagnostics for a class 2 communications dtc U1000 may not lead a technician to a final repair. This U1000 code in the PCM alone will NOT cause any vehicle related symptoms or lights.

Recommendation/Instructions:

The vehicles in question were built without the oil level monitoring hardware. The software is supported by the PCM and the PCM is looking for a signal input from the oil level sensor over class 2 Communications. As a Technician you are to disregard the dtc U1000 that may be set current or history in the PCM ONLY.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.