P0100

Mass-airflow (MAF) sensor circuit malfunction

Detection Conditions

• The signal from the mass airflow sensor to the ECU has fallen below 0.64V or risen above 4.9V.
• The expected input signal from the MAF sensor is calculated by the ECU according to throttle opening angle using the throttle position sensor.  If the intake air flow amount falls below 2.4 g/s for 5 seconds and the throttle opening angle is above 50% with the engine running, the ECU determines that the detected intake air flow amount is too low.
• The expected input signal from the MAF sensor is calculated by the ECU according to engine speed using the crankshaft position sensor.  If the intake air flow amount rises above 53 g/s for 5 seconds and engine speed is less than 2000 rpm with engine running, the ECU determines that the detected intake air flow amount is too high

Diagnostic Support Notes

• This is a continuous monitor (CCM)
• Check engine indicator illuminates if the ECU detects the above malfunction condition during the first drive cycle
• PENDING CODE not available
• FREEZE FRAME DATA is available
• DTC is stored in ECU memory

Possible Causes

• MAF sensor malfunction
• Connector or terminal malfunction
• Short to ground in wiring between MAF sensor terminal B and ECU
• Open circuit in wiring between MAF sensor terminal B and ECU
• Open circuit in MAF sensor ground circuit
• Throttle position sensor malfunction
• Electrical corrosion in MAF signal circuit
• Voltage drops in MAF signal circuit
• Electrical corrosion in MAF ground circuit
• Voltage drops in ground circuit
• ECU malfunction
• Open circuit in wiring between main relay and MAF sensor terminal C

[P0100 - From 2002 Mazda Millenia factory service manual]