P2C20Cold Start Fuel Pressure Regulator A Exceeded Control Limits - Pressure Too High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- MIL after one faulty cold start
- Harsh, loud cold idle or ticking injectors
- Possible reduced power or rich running smell
- Likely causes
- LikelyQuantity control valve on the high-pressure pump stuck in the delivering position
- PossibleWiring or connector fault in the control valve drive circuit
- PossibleRail pressure sensor drifting so the controller overshoots
- RareEngine control software that needs an update
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.