P259DExcessive Time To Enter Closed Loop Turbocharger B 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
- P259D is the turbocharger B version of the closed-loop timing fault. On engines with two separately regulated chargers, the control unit expects the boost regulation of the second unit to switch to feedback operation within a set time, and here it did not. No manufacturer documents P259D publicly with thresholds; the basis is CARB 13 CCR 1968.2, which asks for a malfunction when feedback boost control does not start in time or falls back to default operation. GM's 2018 diesel table illustrates the dependency on the A side: its actuator plausibility checks only run while VGT position feedback is active and no fault is present on the position sensor or the actuator circuit. A stored sensor or actuator fault on charger B is therefore the first thing to repair. P259C covers turbocharger A.
- What you may notice
- Engine warning lamp on
- Reduced power, especially at higher load
- Likely causes
- LikelyFault on position or pressure sensing for charger B
- PossibleActuator B or its control circuit faulty
- RareLeak in the charge air path of charger B
- 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 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.