P259ATurbocharger Boost Control Position Sensor B Performance - Stuck Low
- 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
- P259A applies to engines with a second boost control actuator, for instance a twin-turbo layout or the second stage of a two-stage system, whose position is read by sensor B. The code is stored when that actuator's reported position stays at the low end and stops tracking the command even though the signal is electrically sound. No manufacturer documents P259A publicly. Its logic mirrors P2598 on the A side, where Ford compares requested with actual position and reacts to more than 15 % for 25 s, and GM counts samples with vanes more open than requested. CARB 13 CCR 1968.2 requires the boost control system to report faults that stop it from reaching its target. P259B is the high-side counterpart; circuit faults of sensor B fall under P2586-P2590. Reduced power is the usual result.
- What you may notice
- Engine warning lamp on
- Weak acceleration, notably in the range where charger B works
- Likely causes
- LikelySticking vanes, flap or wastegate on charger B
- PossibleWeak vacuum or electrical supply to actuator B
- PossibleWorn actuator B or misadjusted linkage
- 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: €80 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.