P0104Mass or Volume Air Flow Sensor A Circuit Intermittent
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The mass air flow sensor (MAF) sits between the air filter and the throttle or compressor and measures how much air the engine draws in; fuel quantity, load and ignition are calculated from it. Most are hot-film or hot-wire sensors that output either a voltage or, on GM, Saab and newer Ford systems, a frequency. P0104 covers brief dropouts or jumps in the signal without a permanent low or high fault – the classic sign of a loose contact. In Ford's 2020–2023 petrol summary the code is set once more than 25 short open or short-circuit events have been counted. GM and Saab do not list P0104 in the documents checked; there such dropouts end up under P0102/P0103 or P0101. The trip count is not stated by Ford. Diagnosis means moving the harness while watching the live signal and checking terminals for corrosion and weak tension.
- What you may notice
- Check engine light on, may go out again
- Occasional hesitation, misfire-like stumble, flat spot
- Intermittent rough idle or stalling
- Likely causes
- LikelyLoose contact at the sensor connector (corrosion, spread terminals, broken latch)
- PossibleChafed or partly broken wire moved by the engine
- PossibleSensor electronics dropping out (temperature-dependent)
- RarePoor ground or electrical interference
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.