P00C4
Turbocharger/Supercharger Bypass Valve B Mechanical
Generic OBD-II
Real-world scan data
Seen in
62
scans in the past year
Found in
<0.1%
of scans
<0.1%
of scans that found faults
Appears alongside · share of P00C4 scans
U0428in 83.9% of scans
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Inspect the turbocharger bypass valve for any signs of damage or malfunction
- Clean or replace the turbocharger bypass valve if it is clogged or dirty
- Adjust the turbocharger bypass valve settings to ensure proper operation
- Check and replace any faulty vacuum lines or hoses connected to the turbocharger bypass valve
Common causes
Most likely first
- Faulty turbocharger/supercharger bypass valve
- Blocked/dirty turbocharger/supercharger bypass valve
- Malfunctioning turbocharger/supercharger bypass valve sensor
- Wiring/connectivity issue with the turbocharger/supercharger bypass valve
- Contaminated/deteriorated turbocharger/supercharger bypass valve seals
How to diagnose & fix
Work through it in order
- Loss of power or decreased engine performance
- Engine misfires or hesitates
- Increased fuel consumption
- Illuminated check engine light
- Loud whistling or chirping noise from the turbo/supercharger area
Read & clear P00C4 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.