The sensor in the fuel rail reads lower pressure than the computer requested. The nozzles are not getting enough fuel.
Medium to high. Usually, the car goes into emergency mode, and with a greater drop, it shuts off or does not start.
Most often diesels with Common Rail, but also gasoline ones with direct injection. Filter, pumps, regulators, nozzles.
What does P0087 mean
In the Common Rail, the fuel is kept under very high pressure in a common rail from which it feeds all the nozzles. The high pressure pump creates it, and the regulator and sensor maintain it. If the actual pressure remains below the command, the computer records P0087. The opposite case — pressure too high — is P0088.
Symptoms
- Power loss, emergency mode
- Hard to start, especially on a warm engine
- Engine stalls under load or idling
- Jerking when accelerating
| Can it be driven?
Carefully to the service. If the car stalls or won't start, don't drive it. With diesels, do not drive "on reserve" - air in the system makes the problem worse.
Common reasons
- Clogged fuel filter — the most common and cheapest reason.
- Air in the fuel system — burst hose, loose connection, out of fuel.
- Weak low pressure pump (in the tank) for cars with one.
- Defective pressure regulator or metering valve (P0089).
- Large backflow from the nozzles — worn nozzles return too much fuel.
- Worn out high pressure pump.
- Faulty pressure sensor in the rail.
How we diagnose it
- We compare the commanded and actual pressures at ignition, idle and load.
- We check the filter and fuel supply to the high pressure pump.
- We are doing a backflow test from the nozzles.
- We check the regulator, the dosing valve and the sensor.