P0102: OBD-II code P0102 means the MAF sensor is reporting airflow lower than physically possible — the PCM sees an unrealistically low reading it can't work with.

Symptoms

• Check engine light is on and the engine may run lean, hesitate, or stall at idle.
• Rough idle, poor throttle response, and reduced fuel economy from incorrect fuel metering.
• The engine may barely idle or refuse to run above idle if the MAF signal has dropped to zero.

Common causes

• A contaminated or dead MAF sensor — the hot wire is fouled by oil or dust and reads much too low.
• A damaged or unplugged MAF connector, or a chafed signal wire pulling the signal low or open.
• A cracked intake air boot before the MAF, letting unmetered air enter the engine.

What to do?

Clean the MAF sensor with dedicated MAF cleaner (never brake cleaner). Inspect the intake boot for cracks and the connector for damage. Read live MAF grams-per-second at idle (~4-8 g/s) and 2,500 RPM against factory specs. Replace the MAF if it reads at or near zero after cleaning.