P259CExcessive Time To Enter Closed Loop Turbocharger A Boost Control
- 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
- P259C reports that closed-loop boost control of turbocharger A was not reached within the expected time after its enabling conditions were met. Instead of trimming the actuator from boost or position feedback, the controller stays in open-loop or default mode. CARB 13 CCR 1968.2 requires diesel OBD systems with feedback boost control to report it when control fails to start inside a time window set by the manufacturer, and P259C is the code for that case. No manufacturer publishes thresholds for P259C. Ford's 2023 diesel summary shows why it matters: its underboost check for turbocharger A runs only while boost feedback control is active. Typical root causes are inputs the loop needs, such as a faulty boost or position sensor, or a stored actuator fault. P259D is the turbocharger B equivalent.
- What you may notice
- Engine warning lamp on
- Sluggish or uneven boost build-up
- Likely causes
- LikelyBoost pressure or actuator position sensor fault that blocks closed-loop control
- PossibleActuator A fault, often with its own stored code
- PossibleCharge air leak preventing boost from reaching the range where control starts
- RareEngine control software issue
- 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 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.