Powertrain, generic (extended)

P2CB6 Turbocharger/Supercharger B Boost System Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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.

Likely causes

Leak in the charge air path of charger B
Sticking wastegate or variable vanes of charger B
Restriction in the exhaust upstream or downstream of turbine B
Boost pressure sensor B reading inaccurately

Symptoms

  • MIL on
  • Uneven or reduced power under load
  • Hissing or whistling from the charge air system

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–2,500
Time1–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

turbocharger bwastegate bboost pressure sensor b

Related codes

P2263P2CB7P2CB8P02CAP02CBP0239

References: law.cornell.edu, gsi.ext.gm.com, saabwisonline.com.