P0235Turbocharger/Supercharger Boost Sensor A Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Boost sensor A measures the absolute pressure between charge air cooler and throttle – GM calls it TIAP, Ford TIP – usually combined with an intake air temperature sensor; its voltage rises with pressure. With the ignition on and the engine stopped it must read the same as manifold and barometric pressure. P0235 is the general fault of sensor A's circuit or signal, for modules that do not split low, high and range. GM, Ford and Saab do not use it; Audi documents it on the Q7 TDI together with over- and underboost, so there it also marks an implausible boost value, for example from a charge air leak or jammed turbo vanes. No manufacturer threshold for this code was found. With a sensor fault boost control is switched off and only the base boost of the wastegate spring remains, with a clear loss of power.
- What you may notice
- Check engine light on
- Clear loss of power, only base boost
- Boost reading implausible in a scan tool
- Likely causes
- LikelyConnector at the boost sensor corroded or loose, broken wire
- PossibleBoost sensor faulty, often oily from crankcase ventilation
- PossibleCharge air leak or jammed turbo vanes causing an implausible value
- Rare5 V reference shorted by another sensor
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.