OBD-II · Engine and powertrain (P)
P0100
Mass or volume air flow circuit fault
What it means
The ECU detects a fault in the MAF signal circuit. Intake leaks, restrictions, and contamination affecting otherwise valid readings belong in the P0101 range/performance diagnosis.
Symptoms
- hesitation or flat spots when accelerating
- reduced power, sometimes limp mode
- rough idle or stalling
- black smoke on diesels
- engine warning light
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | failed MAF sensor electronics |
| 02 | open or shorted signal wiring |
| 03 | corroded or loose connector terminals |
| 04 | sensor supply or ground fault |
| 05 | ECU input fault |
What to check, step by step
- 01Inspect the MAF connector and wiring for damage, corrosion or a loose plug
- 02Check the sensor supply and ground with a meter
- 03Read the MAF value in live data: with the key on and engine off it should be near zero, and it should rise smoothly with rpm
- 04Unplug the MAF with the engine idling: if the engine runs better unplugged, the sensor is suspect
- 05Replace the sensor with an OE-quality part if the wiring is good (cheap copies often read wrong)