P0100Mass or Volume Air Flow Sensor A Circuit
- 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. P0100 means the control module gets no usable signal at all. Ford uses it for a broken sensing element on digital sensors (period longer than 1.3 ms, i.e. below about 0.78 kHz, for half a second); on GM's 3.0 V6 in the Saab 9-4X it is set at 0 Hz. Many systems with voltage sensors skip P0100 and report low or high directly. The engine then runs on air mass calculated from manifold pressure, throttle angle and speed; Ford also disables start-stop.
- What you may notice
- Check engine light on
- Rough idle, hesitation, lack of power (substitute value)
- Hard starting or stalling
- Higher fuel consumption
- Likely causes
- LikelyConnector unplugged or corroded, signal or supply wire open
- LikelySensor faulty internally (broken element, failed electronics)
- PossibleSupply fuse or relay failed
- RareControl module input faulty
- 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.