Turbocharger/Supercharger Boost Sensor A Circuit Malfunction
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.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $100 - $400 (parts and labor)
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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
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.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
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
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- 2010-2020 Ford F-150 EcoBoost
- 2008-2018 Volkswagen Jetta TDI
- 2012-2019 Chevrolet Cruze Diesel
- 2011-2019 BMW 535i
- 2014-2021 Subaru WRX
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