Powertrain, generic · Fuel and air metering, auxiliary emission controls
P00C1 Turbocharger/Supercharger Bypass Valve B Control Circuit Low
Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo
Bypass valve B is the compressor recirculation (diverter) valve of turbocharger B, not the wastegate: it lets charge air flow back to the compressor inlet when the throttle closes quickly, so the compressor does not surge. Turbocharger B is the second turbocharger in exhaust flow on series systems and the turbocharger of bank 2 on parallel twin-turbo engines. P00C1 reports too low a voltage, typically a short to ground in the control circuit of this valve; the circuit is monitored continuously.
Likely causes
Wiring or connector damaged by turbocharger heat
Valve coil open or shorted
Output driver in the engine control module faulty
Symptoms
- Check engine light on
- Fluttering or surging noise when lifting off the throttle
- Boost fluctuations, loss of power
Repair estimate
DifficultyMediumDIY possible
Parts and labour€60–350
Time0.5–2 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
turbocharger bypass valve bturbocharger bypass valve wiringengine control module
Related codes
References: law.cornell.edu, gsi.ext.gm.com, newtonnet.co.uk, ms-motorservice.com.