P0102 Mass or Volume Air Flow Circuit Low Input

P0102 indicates a low mass-airflow or volume-airflow input. The signal may be electrically low, missing, or much lower than the airflow the control module expects.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not assume a low MAF signal always means the sensor is bad; wiring, power supply, and air-path faults can produce the same code.

Symptoms of P0102

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0102

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Check the MAF power feed, ground, signal circuit, connector pins, and harness movement near the intake tract.
Compare airflow data with engine speed during snap throttle and steady idle.
Inspect for intake restrictions, disconnected ducting, contamination, or recent service that disturbed the sensor.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.