Diagnostic Aids
- Check the MAF sensor harness to verify that it is not routed too close to secondary ignition wires or coils, any solenoids, relays or motors.
- A low minimum air rate through the sensor bore at idle or during deceleration may cause this DTC to set. Check for any deposits on the throttle plate or in the throttle bore or any vacuum leak downstream of the MAF sensor.
- Check for any contamination or debris on the sensing elements of the MAF sensor.
- Check the air induction system for any water intrusion. Any water that reaches the MAF sensor will skew the sensor and may cause this DTC to set.
- A wide open throttle acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 3-10 g/s at idle to 130 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
- Check for a skewed or stuck ECT sensor.
- Check for a skewed or stuck TP sensor.
- The barometric pressure used to calculate the predicted mass air flow value is initially based on the MAP sensor at key ON. When the engine is running the BARO value is continually updated near wide open throttle. A skewed MAP sensor will cause the calculated MAF value to be inaccurate and may result in a no start condition. The value shown for the MAP sensor parameter varies with the altitude. With ignition switch in RUN position and the engine OFF, 101 kPa is the approximate value near sea level. This value will decrease by approximately 3 kPa for every 1000 feet (305 meters) of altitude.
- A high resistance on the low reference circuit of the MAP sensor may cause this DTC to set.
- A high resistance on the signal or the low reference circuit of the ECT sensor may cause this DTC to set.
- If the condition is intermittent, See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.1L CENTURY, GRAND PRIX & MALIBU article.