What it means
Bypass valve B does not respond to commands as expected. Mechanical issue. Boost control tracks commanded vs. actual manifold pressure; persistent deviation means wastegate, vanes, hose or actuator are not delivering the requested pressure.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The turbocharger or supercharger bypass valve B helps control boost by routing air around the compressor when needed. The engine control module compares the valve’s response with the requested operating range and sets P00C3 when valve B does not behave as expected; this code points to performance outside the expected range, not necessarily an electrical open or short.
Common causes
Most likely first.
- Valve sticking from carbon
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
How to diagnose it
- Use a scan tool to record freeze-frame data and compare commanded and actual boost around the time the fault occurred.
- With the engine off, inspect bypass valve B, its hoses, linkage and connector for looseness, damage, leaks or debris.
- Check that valve B and its actuator move freely through their intended range without binding.
- Inspect the valve B wiring and connector for corrosion, loose pins, chafing or heat damage.
- Use scan-tool commands or the manufacturer's specified test to compare valve B actuator movement with boost response, then test the actuator and circuit as specified by the manufacturer.
Common fixes
- Reconnect or secure a loose valve B hose or electrical connector.
- Repair damaged wiring or replace a corroded connector at the valve B circuit.
- Clean an obstructed bypass valve B if the manufacturer's procedure permits it.
- Repair or replace a sticking valve B, actuator or linkage.
- Repair a boost leak or other fault confirmed by pressure and actuator tests.
Can I keep driving?
Avoid hard acceleration and high boost until the fault is diagnosed; reduced power or limp mode may occur. Continued boost-control problems can worsen engine performance and emissions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.