Mass Air Flow Sensor Circuit High Input

Opposite of P0102. The PCM is seeing a MAF signal higher than the engine could physically be flowing. Usually that's a short to voltage on the signal wire, water inside the sensor or connector, or a failed sensor outputting full-scale. Less commonly: a torn intake boot that creates pulsations the sensor misreads as huge airflow, or aftermarket intake hardware that changes the air column the sensor was calibrated for. Often pairs with rich codes (P0172/P0175) because over-reported airflow means the PCM dumps in too much fuel.

MAF signal exceeds the maximum expected value for the engine size and operating range, typically >5.0 V analog or >15000 Hz on frequency-output sensors with no corresponding RPM/throttle to justify it.

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 1Unplug the MAF. If signal drops to 0 V at the sensor connector, wiring is fine — sensor is failed.
2. 2If signal stays high with sensor unplugged, you have a short to voltage between sensor and PCM. Pin-point with a meter or scope along the harness.
3. 3Inspect for water — under the connector boot, inside the sensor housing. Dry it out, dielectric grease the pins, retest.
4. 4If the vehicle has an aftermarket intake, put OE back on and retest. Wrong-diameter intake tubes throw MAF calibration off badly.
5. 5Scope the signal at snap-throttle. A torn boot before the throttle can create reversion pulses that look like huge airflow spikes — replace the boot.
6. 6Check fuel trims. Big NEGATIVE long-term fuel trim (PCM pulling fuel out) confirms the MAF is over-reporting.

• Short to voltage on MAF signal wire
• Water intrusion into MAF or connector (parked outside, washing engine)
• Failed MAF sensor pegged high
• Aftermarket cold-air intake with wrong-size tube changing airflow profile
• Torn or collapsed intake boot creating signal pulsations
• Corroded MAF connector

MAF sensor $80–$400. Connector pigtail $20–$80. Wiring repair $80–$300.