P0087 – Fuel Rail/System Pressure Too Low (Mercedes-Benz OM651)
Fault code P0087 means "Fuel Rail/System Pressure Too Low". It is common on OM651 (C/E 200–250 CDI, Sprinter, Vito, Viano) engines. Below are the real-world causes, step-by-step tests and OEM part numbers.
Last updated
P0087 quick summary
| Fault code | P0087 |
|---|---|
| Meaning | Fuel Rail/System Pressure Too Low |
| System | Powertrain (Engine & Transmission) |
| Vehicles | Mercedes-Benz |
| Common on | OM651 (C/E 200–250 CDI, Sprinter, Vito, Viano) |
| Severity | High |
| Can I drive? | Not recommended. Limp mode under load, jolting or stalling are typical. |
| Repair cost | €30 – €2,500 |
Symptoms of P0087
- Limp mode when overtaking or on motorway climbs
- Engine jolts or stalls, sometimes a few minutes after a cold start
- Check Engine light, fault may come and go
- Power loss under load
- Sometimes related codes for the quantity control valve (e.g. P0252)
Most common causes of P0087 (most likely first)
Mechanic's Pro Tip
On the OM651, independent specialists see the fuel quantity control valve (Y94) on the high-pressure pump as a frequent cause of P0087 that comes and goes under load. Before you replace it, rule out the cheap things – fuel filter, air in the lines – and check injector return flow and per-cylinder correction values in XENTRY, because a leaking injector also drops rail pressure.
1.Faulty fuel quantity control valve (Y94) on the high-pressure pump
Most likely2.Clogged fuel filter or air in the low-pressure system
3.Faulty rail pressure sensor or pressure regulating valve
4.Leaking injector with excessive return flow
5.Worn high-pressure pump
Step-by-step diagnostic guide
- 1
Read all codes with XENTRY or a Mercedes-capable scanner; note related codes for Y94, the rail pressure sensor or the regulator.
- 2
Log specified vs. actual rail pressure during a full-load drive – the fault often appears only under load.
- 3
Check the fuel filter and low-pressure supply.
- 4
Check per-cylinder quantity correction values and injector return flow in XENTRY; a markedly high return means an internally leaking injector.
- 5
Test the Y94 valve (wiring, resistance, response); after replacing parts, perform any required coding / adaptation.
Frequently asked questions
Is the Y94 valve hard to replace on the OM651?
It sits on the high-pressure pump and access usually requires removing parts such as the EGR pipe and intake elbow. A workshop typically needs about an hour or more.
How much does it cost to fix P0087 on an OM651?
A fuel filter is cheap. An original Y94 quantity control valve costs roughly 150–200 € for the part plus fitting. A high-pressure pump or injectors cost considerably more – injectors must be coded (IMA code) after replacement.
Related fault codes
This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.