P0341 and P0340 Diagnostic Issues on 2008 Pontiac Grand Prix - Intermittent Check Engine Light
My check engine light on my 2008 Pontiac Grand Prix comes on and off intermittently. I've taken it to two different repair shops multiple times. The first visit involved replacing the camshaft position sensor (CMP), spark plugs, and all new spark plug wiring. The second visit included a battery replacement (though I had no starting issues) and a code flash procedure to clear old codes. A pigtail replacement was performed during the most recent service. My engine idle is smooth with no roughness. After returning to two auto parts stores to retrieve diagnostic codes, P0340 and P0341 returned as the original fault codes. I'm now unsure of what to do next or where to look for a proper diagnosis. The vehicle runs fine otherwise—only issue being the intermittent check engine light. Thank you, Nancy.
DTC P0340: Camshaft Position (CMP) Sensor Circuit Malfunction DTC P0341: Camshaft Position Sensor Performance Issue Recommended checks: - Verify voltage at the CMP sensor (should be around 5V under normal conditions) - Perform a KOEO (Key Off, Engine Off) test to check for proper 12V supply on pin N of the ICM (Ignition Control Module) - Confirm ground connection at wire M during KOEO If both voltage and grounding are within specifications, the issue may lie with the CMP sensor's interrupter magnet or internal wiring. Consider replacing the sensor as a next step.