MAF circuit malfunction on Vauxhall — 1.9 CDTi and 2.0 CDTi MAF failures very common, plus 1.4 Turbo petrol Astra/Mokka.
Vauxhall P0100 — MAF circuit malfunction on Vauxhall — 1.9 CDTi and 2.0 CDTi MAF failures very common, plus 1.4 Turbo petrol Astra/Mokka. Typical UK independent garage cost: £100–£320.
What actually causes P0100 on a Vauxhall
Vauxhall 1.9 CDTi (Fiat JTD-shared) Bosch MAF fails by 80k miles — well-documented across Vectra C and Astra H. 2.0 CDTi Insignia MAF degrades similarly. 1.4T A14NET MAF fails reliably by 70k miles. Symptoms: power loss, sometimes limp mode, fuel economy drop and P0100.
Vauxhall engines that log P0100
- 1.7 CDTi (Astra H/J, Corsa D, Meriva)
- 1.9 CDTi (Vectra C, Astra H, Zafira B)
- 2.0 CDTi (Insignia, Astra J, Zafira C)
- 1.4 Turbo (Astra J, Mokka, Insignia)
How we diagnose P0100 on a Vauxhall
- Tech2 / OP-COM — read MAF g/s readings at idle and on throttle
- Visually inspect MAF for oil/dirt contamination
- Inspect air filter and airbox seating
- Pressure-test intake on turbo models
- Replace MAF and clear adaptations
The common misdiagnosis to avoid
On Astra H/Vectra C 1.9 CDTi with P0100 and over 80,000 miles, just replace the MAF as the first move — it's the cause more than 90% of the time and saves diagnostic time.
Vauxhall P0100 repair cost in the UK
Expect £100–£320 including parts and labour at an independent garage. Main-dealer quotes on Vauxhall 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
Stock 1.9 CDTi and 1.4T MAF sensors — both are £45–£65 trade, both fit in 5 minutes, and you'll fit several a month if you have Vauxhall work. Customer happy with same-day turnaround.
Codes usually seen alongside P0100 on Vauxhall
- 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.