Powertrain, generic (extended)

P2C20 Cold Start Fuel Pressure Regulator A Exceeded Control Limits - Pressure Too High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2C20 mirrors P2C1F: during catalyst heating after a cold start the rail pressure overshoots its setpoint because the high-pressure pump supplies more fuel than requested or cannot be throttled back. On GM direct-injection petrol engines the measured pressure must exceed the target by 3 MPa or more, on the map it shares with P228D, for 10 s within 12.5 s (25OBDG03B; in 19OBDG03D only 2 MPa from 20 MPa desired); Type A, MIL on the first trip. GM's 2023 table 23OBDG07 trips when the filtered deviation stays below minus 3 MPa for 7 s, again one trip. Most often a quantity control valve that sticks or a drive circuit fault keeps the pump at full delivery; a drifting rail pressure sensor or software can also be responsible. Too much pressure makes cold idle harsh and noisy; outside warm-up the same fault reads P228D.

Likely causes

Quantity control valve on the high-pressure pump stuck in the delivering position
Wiring or connector fault in the control valve drive circuit
Rail pressure sensor drifting so the controller overshoots
Engine control software that needs an update

Symptoms

  • MIL after one faulty cold start
  • Harsh, loud cold idle or ticking injectors
  • Possible reduced power or rich running smell

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–1,500
Time1–4 h

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

Parts involved

fuel pressure regulator ahigh pressure fuel pump

Related codes

P2C1EP2C1FP228DP228CP0088

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.