P0088 Fuel Rail/System Pressure - Too High
On common-rail diesel and gasoline direct-injection engines, a high-pressure pump feeds the fuel rail, a sensor measures rail pressure, and the engine control module regulates it towards a target from its maps. P0088 is set when the actual pressure stays above the target by more than a threshold for some time. On many gasoline systems the pump can only raise pressure, which is then reduced only by injecting. Typical causes are a sticking pressure control or metering valve, a drifting pressure sensor or, on diesels with a pressure control valve, a blocked return. Real overpressure can cause harsh combustion noise and smoke.
Likely causes
Symptoms
- Check engine light on
- Loss of power or reduced power mode
- Harsh combustion noise
- Smoke from the exhaust
Repair estimate
Typical range across vehicles; the real cost depends on what the testing finds.
What to check first
- Compare sensor reading with a mechanical gauge where possible
- Check regulator wiring
- Inspect return line
Parts involved
Related codes
References: law.cornell.edu, newtonnet.co.uk, gsi.ext.gm.com, saabwisonline.com.