What it means
Turbocharger B turbine speed exceeded its safe limit. Same as P0049 on turbo B. 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
A speed sensor or related control system monitors the rotating turbine in turbocharger B. P00C5 sets when turbine B exceeds its permitted speed, which can happen if boost-control hardware fails to limit turbo speed or if intake or exhaust conditions are abnormal.
Common causes
Most likely first.
- Wastegate or bypass control stuck or not opening as commanded
- Boost control actuator or linkage fault
- Boost control solenoid or wiring fault
- Incorrect boost pressure from an intake or exhaust restriction
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
How to diagnose it
- Record freeze-frame data and compare turbo B speed, requested boost and actual boost in scan-tool data, if available.
- Inspect turbo B intake and charge-air hoses for collapse, restriction, leaks or loose connections.
- Check turbo B wastegate or bypass control, actuator and linkage for sticking, damage or a failure to move as commanded.
- Inspect the turbo B control solenoid wiring and connectors for damage, corrosion or loose pins.
- Check for intake or exhaust restrictions and test the actuator, solenoid and related circuits using the manufacturer's procedure.
Common fixes
- Reconnect or replace a damaged or leaking turbo B hose.
- Repair a loose connector or damaged wiring at the turbo B boost-control circuit.
- Replace a failed boost-control solenoid after confirming the circuit fault.
- Free or repair a sticking wastegate, bypass mechanism or actuator linkage.
- Correct a confirmed intake or exhaust restriction.
Can I keep driving?
Avoid hard acceleration and high engine load; an overspeeding turbo can be damaged and may cause sudden power loss. If the engine enters limp mode, smokes heavily or makes a new high-pitched noise, stop driving and arrange diagnosis.
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.