| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. |
Circuit Description
MAF meter uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through MAF meter. DTC is set when ECM detects an open or short in MAF meter circuit for more than 3 seconds with engine speed at 4000 RPM or less. ECM will operate in fail-safe mode if DTC P0100 is set. Possible causes are
- MAF meter circuit is open or shorted.
- Defective MAF meter.
- Defective ECM.
Diagnostic Aids
After confirming DTC P0100, use scan tool to access CURRENT DATA to confirm mass airflow ratio. If ratio is 0.0 gm/sec., VG circuit may be open or shorted or power source circuit may be open. If ratio is 271.0 gm/sec. or more, EVG circuit may be open. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.