P229DFuel Pressure Regulator B Exceeded Learning Limits - Too High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P229D reports that the learned correction for fuel pressure regulator B has climbed to its upper bound, the opposite of P229C. No manufacturer documents the code publicly, so its logic can only be inferred from the regulator A equivalent P228F: Ford's 2023 diesel summary sets that code after about 10 s when the controller adaptation passes a limit near a 20 % sensor-slope error, and Volvo and Mack link P228F on their truck engines to dirt that reached the high-pressure side. For regulator B, usually the rail pressure valve, a correction pinned at the top points to a valve that needs ever more drive to hold pressure, or a sensor out of calibration. CARB requires such exhausted control authority to be flagged.
- What you may notice
- Check engine light
- Occasional unstable rail pressure or rough idle
- Likely causes
- PossibleRail pressure regulator valve worn or contaminated
- PossibleRail pressure sensor characteristic drifted
- RareContaminated fuel reaching the high-pressure side
- 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.