Mercedes-Benz P0089

Fuel pressure regulator on Mercedes — OM651/OM642 DRV and CP4 pump regulator failure.

Mercedes-Benz P0089 — Fuel pressure regulator on Mercedes — OM651/OM642 DRV and CP4 pump regulator failure. Typical UK independent garage cost: £250–£6000.

What actually causes P0089 on a Mercedes-Benz

Mercedes diesel P0089 needs the same CP4 contamination check as P0087 — if the filter has glitter, the whole system is at risk.

Mercedes-Benz engines that log P0089

• OM651 2.1 CDI
• OM642 3.0 V6 CDI
• M274 2.0 turbo petrol

How we diagnose P0089 on a Mercedes-Benz

1. Read rail pressure live
2. Cut fuel filter open
3. DRV resistance test
4. Quote full system if contamination found

The common misdiagnosis to avoid

DRV-only fix on a contaminated system means injectors and rails will fail within months. Be honest with the customer.

Mercedes-Benz P0089 repair cost in the UK

Expect £250–£6000 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

OM651 P0089 — same approach as P0087. Don't half-fix.

Codes usually seen alongside P0089 on Mercedes-Benz

• P0087
• P0088