Fuel and air

P00C2 — Turbo/Supercharger Bypass Valve B Control Circuit High

Severity: medium Drive with care, to a shop

What P00C2 means

The engine control module drives bypass valve B to release excess boost pressure and protect the turbocharger or supercharger. P00C2 sets when the voltage in that valve's control circuit is higher than expected. Common causes are an open or shorted wire, a poor connector contact or a failed valve.

Symptoms

  • Check Engine Light on
  • Loss of power or inconsistent boost pressure
  • Hesitation under acceleration
  • Reduced fuel economy
  • Limp mode with reduced power
  • Unusual turbocharger noise

Possible causes

  1. Open or shorted wiring in the bypass valve B circuit
  2. Poor connection or corroded connector at the valve
  3. Failed bypass valve B
  4. Faulty turbo actuator or position sensor
  5. Sticking variable geometry mechanism
  6. Charge-air or vacuum leak
  7. Failed ECM (uncommon)

How to diagnose

  1. Read all codes and freeze frame data, and note any other boost-related codes
  2. Inspect the valve B harness and connector for chafing, heat damage, corrosion and loose pins
  3. Check power and ground at the valve connector using the factory wiring diagram
  4. Test the control wire for an open and for a short to voltage
  5. Measure the valve coil resistance and compare it to specification
  6. Command the valve with a scan tool and watch it move through its full range
  7. Compare commanded and actual boost in live data
  8. Inspect charge-air hoses and vacuum lines for cracks and leaks

Common fixes

  • Repair damaged wiring and clean or replace the connector
  • Replace bypass valve B
  • Fix a sticking actuator or replace the actuator and position sensor
  • Replace damaged hoses and fix boost leaks
  • Test the ECM and reflash or replace it only if confirmed faulty

Questions and answers

Can I drive with a P00C2 code?

Briefly and carefully, yes, but the car may lose power or enter limp mode. Have the valve circuit checked soon to avoid stressing the turbo.

What most often causes P00C2?

Most often it is a wiring or connector problem at the valve, such as an open, short or corrosion. The valve itself comes next, and the ECM is rarely at fault.

Will clearing the P00C2 code fix it?

Clearing only turns off the light for a while. If the wiring or valve is faulty, the code will return, so find the cause first.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.