P2CB6Turbocharger/Supercharger B Boost System Performance
- 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
- P2CB6 rates the boost control loop of charger B as a whole: the pressure produced by the second turbocharger or supercharger strays too far, upward or downward, from what the engine module requests in steady closed-loop operation. It is the B counterpart of P2263 and only applies to engines with two separately controlled chargers. No manufacturer documents P2CB6 publicly. GM's A version on its 2018 diesels counts 400 failures in 500 samples between 2,250 and 4,500 rpm at a desired boost of 130–300 kPa and names leaks after the compressor or exhaust restrictions as targets, Type A. CARB requires underboost, overboost and slow-response detection. Unlike P02CA/P02CB, which name the direction, this code judges overall control quality.
- What you may notice
- MIL on
- Uneven or reduced power under load
- Hissing or whistling from the charge air system
- Likely causes
- LikelyLeak in the charge air path of charger B
- PossibleSticking wastegate or variable vanes of charger B
- RareRestriction in the exhaust upstream or downstream of turbine B
- RareBoost pressure sensor B reading inaccurately
- 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: €80 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.