P0104 Mass or Volume Air Flow Circuit Intermittent

P0104 indicates an intermittent mass-airflow or volume-airflow circuit fault. The airflow signal drops out or becomes implausible only under some conditions.

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 clear an intermittent airflow code without a harness and connector check; short test drives may not reproduce it immediately.

Symptoms of P0104

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 P0104

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

Watch MAF data while gently moving the harness and repeating the freeze-frame load and RPM conditions.
Inspect connector fit, terminal tension, chafed wiring, intake duct movement, and sensor contamination.
Compare fuel trims and airflow data during the dropout to confirm whether the fault is signal-related or airflow-related.

Related OBD-II codes

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