Summary
P0102 means the MAF sensor signal is lower than the PCM expects for current operating conditions. The sensor is reporting too little airflow — either because the element is contaminated, the sensor is disconnected, or there's a wiring fault pulling the signal low. The most common cause is a dirty MAF element (30%), followed by a disconnected MAF connector (25%) and wiring issues (20%). Start with a visual check of the connector and a $8 MAF cleaning.
Severity: Moderate
Safe to drive: Yes, short distances — the PCM uses estimated airflow as a fallback
Repair cost: $0–$300 depending on cause
DIY difficulty: Easy to Moderate
What does P0102 mean?
The MAF sensor sends a voltage or frequency signal to the PCM that corresponds to the mass of air flowing into the engine. At idle, the signal is low. Under heavy throttle, the signal is high. P0102 sets when the MAF signal is lower than the minimum threshold the PCM expects — essentially, the sensor says "barely any air" when the engine is clearly getting more.
Unlike P0100 (general circuit fault) or P0101 (range/performance), P0102 specifically indicates the signal is too low. This could mean the signal is near zero (disconnected sensor), stuck at a low voltage (dirty element or failing sensor), or dropping below the valid range (wiring fault).
The PCM responds by substituting estimated airflow from throttle position and RPM data. The engine keeps running but won't perform well — expect poor throttle response, rough idle, and possible stalling.