Powertrain, generic · Fuel and air metering, auxiliary emission controls

P009F Fuel Pressure Relief Control Stuck On

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

The fuel pressure relief control is an electrically controlled valve on the fuel rail that the engine control module opens to reduce rail pressure deliberately, for example on overrun, on load drops or when the engine is switched off. It differs from the purely mechanical pressure relief valve, which opens passively at overpressure, and from the pressure regulator, which controls pressure continuously. Manufacturer documents show this code mainly on heavy-duty diesel engines. P009F means the valve stays open or leaks internally: rail pressure collapses or cannot be built up. Manufacturer bulletins name internal leakage of this valve as a known fault; low rail pressure codes often appear at the same time.

Likely causes

Valve leaking internally or stuck open
Fuel contamination
Short circuit keeping the valve energised

Symptoms

  • Check engine light on
  • Hard starting
  • Reduced power
  • Low rail pressure codes

Repair estimate

DifficultyHardWorkshop job
Parts and labour€300–900
Time1.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel pressure relief control valvefuel pressure relief valve wiringfuel rail

Related codes

P009EP009BP0087P0093

References: law.cornell.edu, static.nhtsa.gov, de.wikipedia.org.