What it means
The PCM detected a malfunction in the Turbocharger/Supercharger Boost Sensor A circuit. This code indicates a sensor-circuit fault; it does not by itself establish that the signal failed plausibility checks or that boost will be limited.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Boost pressure sensor A reports pressure in the turbocharger or supercharger intake system to the control module. P0235 sets when the module detects an electrical fault in sensor A’s circuit; it does not by itself mean the boost reading is implausible or that a boost leak is present.
Common causes
Most likely first.
- Boost pressure sensor failed
- Wiring or connector fault
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
How to diagnose it
- Record freeze-frame data and check scan-tool readings for boost sensor A and related pressure sensors with the engine off and running.
- Locate sensor A using the vehicle’s service information, then inspect its connector and nearby wiring for loose pins, corrosion, moisture, or damaged insulation.
- Check the sensor circuit’s reference, ground, and signal using the wiring diagram and compare results with the manufacturer’s specification.
- Test continuity and shorts in the sensor A wiring with the circuit safely isolated, paying attention to sections routed near heat or moving parts.
- If the circuit checks out, test boost sensor A and its signal response using the manufacturer’s diagnostic procedure.
Common fixes
- Reconnect or clean a loose or corroded sensor A connector and repair damaged terminals.
- Repair an open or short in the boost sensor A wiring.
- Replace boost pressure sensor A if its output fails the specified circuit tests.
- Repair a module fault only after the sensor and its wiring have been verified.
Can I keep driving?
If the vehicle has reduced power or enters limp mode, avoid overtaking, towing, and hard acceleration because boost control may be limited or unreliable. Stop driving if it runs roughly, produces heavy smoke, or loses power to the point that it cannot keep up safely.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.