Mercedes-Benz P0087

Fuel rail pressure too low on Mercedes OM651/OM642 diesel — HP pump shaft wear (Bosch CP4) and fuel contamination.

Mercedes-Benz P0087 — Fuel rail pressure too low on Mercedes OM651/OM642 diesel — HP pump shaft wear (Bosch CP4) and fuel contamination. Typical UK independent garage cost: £600–£6000.

What actually causes P0087 on a Mercedes-Benz

Bosch CP4 high-pressure pumps on OM651/OM642 are sensitive to fuel quality — once they start shedding swarf, contamination spreads through rails and injectors. Catch it early at P0087 and you save the injectors; ignore it and you're £4-6k deep.

Mercedes-Benz engines that log P0087

• OM651 2.1 CDI (C/E/Vito/Sprinter)
• OM642 3.0 V6 CDI (E/ML/GL)

How we diagnose P0087 on a Mercedes-Benz

1. Read rail pressure live — sudden drops under load = swarf
2. Cut open fuel filter and inspect for glitter
3. Check VIN for any goodwill / service campaign coverage
4. Quote correctly: full system replacement if contamination confirmed

The common misdiagnosis to avoid

Many garages fit just the HP pump and clear codes — leaves swarf in injectors and rails. The full Bosch remedy is pump + injectors + rails + lines.

Mercedes-Benz P0087 repair cost in the UK

Expect £600–£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.

Service campaign / TSB note

Mercedes has issued goodwill on selected OM651 CP4 failures within 7 years/100k — always check.

Bob's workshop tip

OM651 P0087 — never fit just the HP pump. Customers who say 'do the cheap fix' are back in 8 weeks with a £6k bill and an injector quote.

Codes usually seen alongside P0087 on Mercedes-Benz

• P0088
• P0089

Symptoms drivers report with P0087

• Sudden loss of power on the motorway — car drops into limp mode at exactly 2,500 RPM
• Restarts fine after a key-cycle, then relimps under load 20 minutes later
• Hard cold-starting: cranks for 4–6 seconds before catching
• Uneven idle with a diesel-knock 'nail' from cold
• MPG drops 3–7 mpg before the light even comes on
• Metal glitter in the fuel filter housing = CP4 pump has already grenaded

Repairs that clear P0087

• Replace fuel filter first (cheap, fast)
• Test rail pressure with scan tool
• Injector leak-off test (diesel)
• Replace HPFP only if proven by pressure test

For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0087 guide.