MAF circuit malfunction on Audi — same VAG Bosch HFM failures as VW, plus more common across A4/A6 2.7/3.0 TDI V6.
Audi P0100 — MAF circuit malfunction on Audi — same VAG Bosch HFM failures as VW, plus more common across A4/A6 2.7/3.0 TDI V6. Typical UK independent garage cost: £120–£360.
What actually causes P0100 on a Audi
Audi 2.0 TDI MAF failures track exactly with VW — Bosch HFM7 unit degrades around 100k miles. 2.7/3.0 TDI V6 Audis are particularly prone because the higher airflow stresses the sensor element. 2.0 TFSI MAF failure is rarer but does happen by 100k miles on heavy-use cars.
Audi engines that log P0100
- 1.9/2.0 TDI (A3, A4, A6)
- 2.0 TFSI (A3, A4, A5, A6)
- 2.7/3.0 TDI V6 (A4, A6, Q5, Q7)
How we diagnose P0100 on a Audi
- VCDS — read MAF g/s and compare to expected (idle ~5 g/s, full throttle ~120+ g/s)
- Inspect intake from airbox to turbo for splits
- Replace MAF (genuine Bosch part essential)
- Clear long-term and short-term adaptations
- Road-test and re-check values
The common misdiagnosis to avoid
Avoid the Audi dealer's 'full induction system service' on a P0100-affected 2.0 TDI — at £400+ it's overkill when the £140 MAF is the simple fix.
Audi P0100 repair cost in the UK
Expect £120–£360 including parts and labour at an independent garage. Main-dealer quotes on Audi are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.
Bob's workshop tip
If a customer with a 2.7 TDI A6 brings P0100 and a complaint of 'sluggish' — replace MAF, then sell them an intake walnut blast for the carbon build-up that's almost certainly also there. Two-job easy upsell.
Codes usually seen alongside P0100 on Audi
- P0101
- P0102
- P0299
- P0401
Symptoms drivers report with P0100
- Black smoke on diesel acceleration (over-fuelling because ECU can't trust the airflow reading)
- Rough or 'hunting' idle at traffic lights — RPM wanders between 700 and 950
- Hesitation off the mark, then a sudden shove of power as the ECU falls back to a default air-map
- MPG drops 5–10 in mixed driving — the ECU can't run closed-loop trims without valid MAF data
- Engine surges at steady 50–60 mph motorway cruise
- Sometimes resets itself after key-off / key-on and drives normally for a day
- Often stored alongside P0101 (range) or P0102 (low input) — same root cause
Repairs that clear P0100
- Clean MAF with dedicated cleaner spray
- Replace MAF sensor
- Inspect wiring and connector
- Replace air filter
For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0100 guide.