OBD-II code · Powertrain (generic)
P00C4 Turbocharger/Supercharger Bypass Valve B - Mechanical
Mechanical fault detected at bypass valve B — broken linkage, jammed valve, or seized actuator rod. Boost control tracks commanded vs. actual manifold pressure; persistent deviation means wastegate, vanes, hose or actuator are not delivering the requested pressure.
Is it safe to drive with P00C4?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyLinkage broken or seized
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 2–8 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Bypass Valve B, Linkage
Related codes
- P25FCTurbocharger/Supercharger Bypass Valve C - Mechanical
- P00C1Turbocharger/Supercharger Bypass Valve B Control Circuit Low
- P00C2Turbocharger/Supercharger Bypass Valve B Control Circuit High
- P00C3Turbocharger/Supercharger Bypass Valve B Control Circuit Range/Performance
- P00C5Turbocharger/Supercharger B Turbine Overspeed
- P00C6Fuel Rail Pressure Too Low - Engine Cranking Bank 1
- P00C7Intake Air Pressure Measurement System - Multiple Sensor Correlation Bank 1
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.