Mercedes-Benz P0100

MAF circuit malfunction on Mercedes — OM651 diesel MAF and M271/M272/M276 petrol MAF all fail with mileage and EGR contamination.

Mercedes-Benz P0100 — MAF circuit malfunction on Mercedes — OM651 diesel MAF and M271/M272/M276 petrol MAF all fail with mileage and EGR contamination. Typical UK independent garage cost: £160–£520.

What actually causes P0100 on a Mercedes-Benz

OM651 MAF degrades from EGR blow-back contamination — same mechanism as BMW N47. M271 Kompressor petrol has a long-running MAF reliability issue exacerbated by intake manifold flap problems. M272 V6 MAF is more robust but still fails by 120k miles. P0100 on Sprinter vans is usually MAF contamination from blow-by gases.

Mercedes-Benz engines that log P0100

• OM651 2.1 diesel (C/E/GLK/Sprinter)
• OM642 3.0 V6 CDI (E/S/ML)
• M271 1.8 Kompressor petrol
• M272 3.5 V6 petrol

How we diagnose P0100 on a Mercedes-Benz

1. Xentry / Star — read MAF kg/h live data and compare to expected map
2. Inspect for EGR blow-back contamination
3. Check intake manifold flap actuator (M271)
4. Replace MAF — use OE Bosch part, generic eBay MAFs fail within months
5. Clear adaptations and road-test

The common misdiagnosis to avoid

Mercedes main dealer quotes for 'fuel and air system diagnostic' (£200+) on a high-mileage OM651 with P0100 are rarely necessary — go straight to a genuine MAF replacement.

Mercedes-Benz P0100 repair cost in the UK

Expect £160–£520 including parts and labour at an independent garage. Main-dealer quotes on Mercedes-Benz 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

On any Mercedes with P0100, only use genuine Bosch (or Pierburg on OM651) — the cheap aftermarket sensors will read out of spec within weeks and customer comes back furious.

Codes usually seen alongside P0100 on Mercedes-Benz

• 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.