P0102Mass or Volume Air Flow Sensor A Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- 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. P0102 means the signal is below its electrical lower limit – a frequency that is too low or a voltage that is too low. Documented limits: GM petrol 450 Hz or less, GM diesel below 276 Hz, Ford digital below 1.5 kHz for 5 s, Ford analogue below 0.244 V. 'Low' describes the signal: typically an open or grounded signal wire, missing supply voltage or failed electronics. Saab notes that a large leak between sensor and throttle can also cause it. GM and Saab need two trips; the engine runs on a calculated substitute value.
- What you may notice
- Check engine light on
- Lack of power, hesitation, substitute value mode
- Rough idle or stalling
- Higher fuel consumption
- Likely causes
- LikelySignal wire open or shorted to ground, connector corroded or loose
- LikelySensor electronics failed
- PossibleMissing supply voltage (fuse, relay) or poor ground
- RareLarge leak or disconnected duct between sensor and throttle
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · 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.