P0235–P0239 Turbocharger/Supercharger Boost Sensor A Circuit
The control unit has found a fault in this part's electrical circuit, but the code does not say what kind (a broken wire, a short or a signal out of range). Check the connector and wiring before replacing the part.
Can you drive it? The car is most likely in limp mode with boost cut. It is drivable gently, but it will not make full power and should not be driven hard until it is fixed.
Which code is which
Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.
| Code | Definition | Severity |
|---|---|---|
P0235 | Turbocharger/Supercharger Boost Sensor A Circuit | Investigate soon |
P0239 | Turbocharger/Supercharger Boost Sensor B Circuit | Investigate soon |
The definition
P0235: Turbocharger/Supercharger Boost Sensor A Circuit.
P0235 is a powertrain code (the engine or gearbox), defined by the SAE standard - it means the same thing on any make of car, and any generic OBD-II reader will decode it.
What to check first
Cheapest and fastest checks first:
- Read the freeze-frame data stored with the fault - engine speed, load and temperature at the moment it logged tell you whether this happens cold, hot or under load.
- Check the connector at the part for corrosion, and that it is fully seated.
- Clear the code and see whether it returns, and under what conditions.
Reading the code is the easy part
A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.
VAGPULSE reads your engine ECU's fault codes and the live measuring blocks behind them, and clears the codes once you have fixed the fault. On the engine it also does what a generic OBD reader cannot on a VAG: coding, adaptations, and Stage 1–3 flashing on Bosch ME7 petrol ECUs, with a backup saved every time it reads your ECU.
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Common questions
What does P0235 mean?
P0235 means Turbocharger/Supercharger Boost Sensor A Circuit. The control unit has found a fault in this part's electrical circuit, but the code does not say what kind (a broken wire, a short or a signal out of range). Check the connector and wiring before replacing the part.
Can I drive with P0235?
The car is most likely in limp mode with boost cut. It is drivable gently, but it will not make full power and should not be driven hard until it is fixed.