P0102 — The Mass Airflow Sensor (MAF) Sensor is unplugged or the wiring is damaged, Loose or corroded electrical terminals in the MAF Sensor circuit, Faulty MAF Sensor

Causes

• MAF sensor unplugged or connector not fully seated
• Corroded, bent or loose terminals at MAF connector
• Open or shorted wiring in MAF signal, power or ground circuits
• Blown fuse or poor power/ground feed to the MAF
• Failed or contaminated MAF sensor element
• PCM input fault (rare)

Symptoms

• Malfunction Indicator Lamp (MIL) illuminated
• Rough idle, hesitation, stalling or poor throttle response
• Reduced engine power or limp mode
• Hard starting or no start in severe cases
• Poor fuel economy; long-term fuel trim indicating lean condition
• Surging or inconsistent idle

What to check

• Read stored freeze-frame data and confirm P0102 is current or intermittent
• Visually inspect MAF connector, terminals and wiring for damage or corrosion
• Ensure MAF connector is fully seated and locking tab engaged
• Scan live MAF sensor data (raw counts, voltage or frequency) at key on/engine off and while idling/revving
• Check for correct MAF supply voltage (often 5 V or battery depending on design) and good ground
• Back-probe signal wire and verify expected signal behavior while revving engine

Signal parameters

• Typical idle MAF voltage: roughly 0.5–1.5 V (varies by sensor type)
• Typical WOT MAF voltage: approaches 4.0–5.0 V for voltage-type sensors
• Frequency-type MAFs: low hundreds Hz at idle, increasing to kHz at higher rpm
• Expected behavior: signal should rise smoothly with engine speed/load; a constant near 0 V or stuck low indicates low-input fault
• Reference/power supply commonly ~5 V (verify per vehicle service data)

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