P0100 Mass or Volume Air Flow Circuit Malfunction

P0100 points to a mass-airflow or volume-airflow circuit malfunction. The airflow sensor signal or circuit is outside what 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 clean or replace the MAF sensor before checking wiring, intake leaks, air-filter fitment, and sensor power/ground.

Symptoms of P0100

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 P0100

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

Compare MAF grams-per-second or calculated load with RPM, throttle angle, MAP data, and fuel trims.
Inspect sensor power, ground, signal wiring, connector terminals, air-filter sealing, and intake ducting after the sensor.
Check for contamination, aftermarket intake changes, intake leaks, or recent service that disturbed the air meter.

Related OBD-II codes

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