P229BFuel Pressure Regulator B 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
- How the car detects it
- P229B flags rail pressure that stays above target while fuel pressure regulator B should be holding it. GM's 2018 diesel table, where regulator B is the rail pressure regulator valve, runs this check with the valve in closed-loop control and under the same enable conditions as P229A (fuel level, ambient pressure and temperature), mirroring the overpressure test P228D of the metering unit, and rates it Type B. A valve that sticks closed or cannot open far enough, a drive signal that keeps it energised, or a rail pressure sensor reading high are the classic causes. If pressure keeps climbing to the absolute ceiling, P2293 follows. P229A is the deficit case, P228D the same fault seen through regulator A.
- What you may notice
- Check engine light
- Harder combustion noise
- Reduced power in some cases
- Likely causes
- LikelyRail pressure regulator valve sticking closed
- PossibleRail pressure sensor reading too high
- RareValve drive signal stuck on (wiring or module)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.