P233AFuel Pressure Regulator C Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Fuel pressure regulator C is a third pressure actuator that only a few high-pressure systems have; which valve carries the letter is up to the manufacturer. GM's 2025 diesel table 25OBDG04B assigns C to a second fuel metering unit valve on the pump, driven by the ECM through a high-side and a low-side switch. P233A is logged when, with the valve commanded on, almost no current flows between the two drivers, i.e. the loop resistance looks higher than 200 kOhm; samples are taken every 100 ms above 11 V system voltage, and the fault is Type A, so the MIL comes on in the first trip. GM bulletin 21-NA-149 lists P233A for the 3.0L LM2 Duramax among codes caused by a chafed engine harness. P233B and P233C cover shorts; delivery can falter while the valve is dead.
- What you may notice
- Check engine light on in the first trip
- Rail pressure deviates, hesitation or reduced power
- Possibly hard starting or stalling
- Likely causes
- LikelyValve connector loose, corroded or a terminal pushed back
- PossibleEngine harness wire broken where it rubs on brackets or clamps
- PossibleCoil of the metering valve interrupted
- RareOutput driver in the engine control module faulty
- 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: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.