Severity: Fix within days. Drive with caution and watch for new symptoms.
On GM vehicles, the computer has not learned the small variations in the crankshaft position signal, which it needs to detect misfires accurately. This usually appears after a sensor or computer replacement.
A scan tool is needed to run the crankshaft position variation relearn procedure.
The car usually runs fine, but misfire detection will not work correctly until the relearn is done.
You can drive short distances carefully; watch for worsening symptoms. The car usually runs fine, but misfire detection will not work correctly until the relearn is done.
The most common causes are: Crankshaft position sensor replaced without a relearn; Engine computer replaced; Failing crankshaft position sensor. A scan tool and a visual check of the parts above is where a technician starts.
A scan tool is needed to run the crankshaft position variation relearn procedure.
