P229CFuel Pressure Regulator B Exceeded Learning Limits - Too Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P229C means the learned correction for fuel pressure regulator B has reached its lower bound. No manufacturer documents this code publicly. The matching check for regulator A is described by Ford for its 2023 diesels: the controller adapts at steady rail pressure of 600 bar or more and stores P228E or P228F when the adaptation would exceed roughly a 20 % sensor-slope error. On systems with two regulators, such as GM diesels with a pump metering unit (A) and a rail pressure valve (B), the B value describes the learned behaviour of that spill valve. CARB requires a monitor to report a pressure control that has used up its adjustment authority. Expect a lit MIL with little drivability effect; P229D is the upper bound.
- What you may notice
- Check engine light
- Usually no noticeable change in driving
- Likely causes
- PossibleRail pressure regulator valve characteristic drifted
- PossibleRail pressure sensor characteristic drifted
- RareAdaptation values not reset after a component replacement
- 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: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.