Powertrain, generic (extended)

P2CB7 Turbocharger/Supercharger Boost Pressure B Not Detected - Mechanical

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2CB7 states that charger B delivers practically no boost although the operating point calls for it, and that the reason is likely mechanical rather than electrical: the pressure measured after the second compressor hardly rises above ambient. It mirrors P2262 for charger A and is relevant only to engines with two separately monitored boost paths. No manufacturer documents P2CB7 publicly. For the A version, Volvo technical journal 31319 traced P2262 on a 2016 four-cylinder engine to a fresh-air hose that had slipped off the air filter housing. CARB requires boosted engines to detect underboost. While P02CB measures a shortfall against target, P2CB7 stands for boost missing altogether; acceleration is flat and torque is often limited.

Likely causes

Intake or charge air hose of charger B detached or split
Wastegate or bypass of charger B stuck open
Damaged or seized turbocharger B
Actuator linkage or vacuum supply to charger B failed

Symptoms

  • Clearly flat acceleration
  • MIL on, power limited
  • Unusual hissing or no turbo sound

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–3,000
Time0.5–6 h

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

Parts involved

turbocharger bwastegate bboost pressure sensor b

Related codes

P2262P2CB6P2CB8P02CBP0239

References: law.cornell.edu, static.nhtsa.gov.