Powertrain, generic (extended)

P2C9D Fuel Pressure Regulator C Exceeded Control Limits - Pressure Too High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2C9D reports that the fuel pressure in the section governed by regulator C stays above its target although that regulator is already reducing delivery as far as it can. A third regulator letter is only needed where an engine has several pressure control elements, for instance two high-pressure pumps or separate rail circuits. No manufacturer documents P2C9D publicly. The closest published logic is GM's for regulators A and D (tables 23OBDG07 and 24OBDG07): measured and desired rail pressure may differ by no more than 3 MPa for a few seconds before a one-trip fault is stored. CARB demands a fault once fuel pressure control runs out of authority. Expect a hard, noisy idle or reduced power; P2C9E covers the underpressure side of the same regulator.

Likely causes

Quantity control valve of circuit C sticking in the delivery position
Rail pressure sensor of that circuit reading too high
Wiring or connector fault keeping the valve from being switched
Outdated engine control calibration

Symptoms

  • MIL on, often after a single trip
  • Harsh or noisy idle, especially when cold
  • Reduced engine power

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,200
Time1–4 h

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

Parts involved

fuel pressure regulator cfuel rail

Related codes

P2C9EP2C9FP2C00P228DP229BP0088

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.