P02CBTurbocharger/Supercharger B Underboost Condition
- 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
- Turbocharger B is a second, separately controlled turbo – on twin-turbo or two-stage systems, or one per bank. No manufacturer using the turbo B codes was found; twin-turbo engines such as GM's 3.0 V6 and Ford's 3.5 EcoBoost report boost faults under P0234/P0299 with a shared boost sensor, so the description follows CARB and the turbo A codes. P02CB means actual boost of turbo B stays below target although the control demands more; for turbo A, GM uses 30–55 kPa (petrol) or 10–50 kPa (diesel). Typical causes are a charge air leak on that side, a wastegate stuck open or a worn turbo. Power is then limited.
- What you may notice
- Check engine light on
- Clear lack of power
- Whistling with a leak, limp mode
- Likely causes
- LikelyCharge air leak (hose, cooler, clamp) on side B
- PossibleWastegate B stuck open or control valve faulty
- PossibleTurbo B worn (bearing play, compressor wheel)
- RareExhaust leak ahead of turbine B
- 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: €50 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.