Failure Conditions

Spark value of 0.3 degrees (VIN Y) or 3 degrees (VIN 9) will increment until a maximum of 21 degrees is reached. If knock is not detected for one second at maximum spark, Code P131 will set.

1. Checks if Code P132 was set due to circuit problem.
2. Checks knock sensor's ability to detect an induced spark.

Fig 1: Code P131 Schematic, Active Knock Sensor Failure

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code P131 Diagnostic Flow Chart, Active Knock Sensor Failure

Courtesy of GENERAL MOTORS CORP.