Results of Faulty Knock Sensor Operation

Loss of the KS signal causes the PCM to operate in fail safe mode. In fail safe mode the PCM commands maximum spark retard. A KS that falsely indicates detonation can cause the PCM to retard the ignition timing unnecessarily. Reduced spark advance can cause any of the following conditions:

• Poor fuel economy
• Sluggish engine performance
• Higher exhaust emissions

A KS that fails to detect detonation can cause the PCM to control the ignition timing as if no detonation were occurring. Failure of the PCM to retard the ignition timing when necessary could cause any of the following concerns:

• An excessive engine detonation
• Engine damage during heavy engine loads
• Higher exhaust emissions