Diagnostic Aids

Inspect for the following conditions:

1. An incorrectly routed harness. Inspect the harness of the MAF sensor in order to verify that it is not routed too close to the following components:
   • The ignition cassette.
   • Any solenoids.
   • Any relays.
   • Any motors.
2. Any excessive deposits on the throttle plate or in the throttle bore.
3. A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any vacuum leaks downstream of the MAF sensor.
4. A skewed or stuck TP sensor.
5. A Wide Open Throttle (WOT) acceleration from a stop should cause the MAF sensor g/s display on the scan tool to increase rapidly. This increase should be from 3-10 g/s at idle to 190 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.
6. A skewed or stuck TP sensor.
7. The Barometric Pressure (BARO) that is used to calculate the predicted mass airflow value is initially based on the MAP sensor at key on. When the engine is running the BARO value is continually updated near WOT. A skewed MAP sensor will cause the calculated mass airflow value to be inaccurate. The value shown for the MAP sensor display varies with the altitude. With ignition on and engine off, 101 kPa is the approximate value near sea level. This value will decrease by approximately 3 kPa for every 305 meters (1000 feet) of altitude.
8. High resistance on the ground circuit of the MAP sensor can cause this DTC to set.
9. Any loss of vacuum to the MAP sensor can cause this DTC to set.

Condition may be related to aftermarket accessories. If the condition is intermittent, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.

Fig 1: Altitude vs. Barometric Pressure Table

Courtesy of GENERAL MOTORS CORP.