Turbocharger/Supercharger Boost Sensor A Circuit Malfunction
What does P0235 mean?
The P0235 code means the vehicle's onboard diagnostic system has detected: Turbocharger/Supercharger Boost Sensor A Circuit Malfunction. This is a moderate severity code.
Common Symptoms
- Check Engine Light illuminated
- Engine enters limp mode or reduced power
- Poor acceleration and turbo lag
- Erratic boost readings on gauge
- Black smoke from exhaust under boost
Probable Causes (Ranked by Likelihood)
- Faulty boost pressure sensor (MAP sensor) Very High
- Damaged or corroded boost sensor wiring High
- Boost leak between turbo and sensor Moderate
- Clogged or blocked boost sensor vacuum line Moderate
- PCM/ECM malfunction Low
Step-by-Step Diagnostic Procedure
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Read boost sensor voltage with scan tool at key-on engine-off -- should read approximately 1.0-1.5V (atmospheric pressure)
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Compare boost sensor reading to a known-good mechanical gauge during a boost test
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Inspect the boost sensor connector for corrosion, bent pins, or water intrusion
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Check the 5V reference voltage and ground at the sensor connector
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Clear the code and road test -- if it returns, replace the boost pressure sensor
Frequently Asked Questions
Can I drive with code P0235?
You can drive short distances, but the engine will likely be in limp mode with reduced power. The PCM cannot properly control boost without an accurate sensor reading.
Is the boost sensor the same as the MAP sensor?
On many turbocharged vehicles, the boost pressure sensor is essentially a MAP (Manifold Absolute Pressure) sensor mounted in the intake manifold or intercooler piping. They measure the same thing -- intake manifold pressure.
Can a boost leak trigger P0235?
Yes. A significant boost leak between the turbo and the sensor can cause readings that are lower than expected, though this more commonly triggers an underboost code like P0299.