Fuel and air

P00C3 — Turbo/Supercharger Bypass Valve B Control Circuit Range/Performance

Severity: medium Drive with care, to a shop

What P00C3 means

The engine control module uses a bypass valve on the turbocharger or supercharger to release excess boost pressure and protect the engine and turbo. P00C3 sets when the position or response of valve B does not match what the ECM commands, or the control circuit signal is out of its expected range. The cause may be the valve or actuator itself, the wiring, or a boost or vacuum leak.

Symptoms

  • Check Engine light on
  • Reduced power or turbo lag
  • Erratic boost pressure
  • Whistling or hissing from the turbo or intake piping
  • Limp mode with limited power
  • Unusual turbocharger noise

Possible causes

  1. Faulty bypass valve B or its actuator
  2. Damaged wiring or corroded connector in the control circuit
  3. Sticking valve or variable geometry mechanism
  4. Faulty actuator position sensor
  5. Charge-air or vacuum leak, including cracked or loose hoses
  6. ECM software or control signal fault

How to diagnose

  1. Scan for all codes and review freeze frame data, noting any other boost-related codes
  2. Inspect intake piping, clamps, intercooler and vacuum hoses for cracks and leaks
  3. Inspect the valve wiring and connector for chafing, corrosion, and check power and ground
  4. Measure valve coil resistance and test the control circuit back to the ECM
  5. Compare specified and actual boost pressure in live data
  6. Command the actuator with a scan tool and check movement over its full range
  7. Check the position sensor and look for binding or carbon buildup
  8. Check for available ECM software updates

Common fixes

  • Replace the bypass valve or actuator
  • Repair wiring and connectors to the valve
  • Fix boost leaks and replace damaged hoses
  • Clean or replace a sticking turbo mechanism
  • Update or reflash the ECM if the manufacturer provides it

Questions and answers

What does P00C3 mean?

It is a generic OBD-II code meaning the ECM sees the control circuit of turbo or supercharger bypass valve B performing out of range. The usual culprits are the valve, actuator, wiring or a boost leak.

Can I drive with P00C3?

Briefly and gently, yes, though power may be limited. Driving long with faulty boost control can damage the turbo, so have it diagnosed soon.

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.