P0234 — Turbocharger/Supercharger "A" Overboost Condition
Boost pressure exceeded the upper limit during commanded full load. The ECU usually drops fuel and ignition or commands the wastegate fully open to protect the engine; persistent overboost can crack pistons or rings.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Turbocharger
- Wastegate actuator
- Boost pressure sensor
- Vacuum lines
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Wastegate stuck closed (carbon, broken linkage)
- Boost control solenoid failed
- Vacuum/pressure line cracked
Possible symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
- Reduced-power or limp mode may occur
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.