P0237
PowertrainTurbocharger/Supercharger Boost Sensor "A" Circuit Low
The turbocharger boost pressure sensor 'A' circuit is reading too low. The signal voltage is below what the ECU expects to see at any operating condition, suggesting either a sensor fault or a wiring issue.
ⓘ Information only. This page provides general educational information about fault code P0237. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0237 mean?
P0237 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Turbocharger/Supercharger Boost Sensor "A" Circuit Low.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light
- • Possibly limp mode if the ECU thinks boost has failed
- • Loss of power, sometimes only at higher revs
- • Sluggish acceleration
- • On diesels: possible black smoke under load
Possible causes
Causes commonly associated with P0237, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Failed boost sensor reading low (most common, sensors fatigue)
- 2. Wiring shorted to ground at any point in the run
- 3. Connector unplugged, oil-contaminated, or with backed-out pins
- 4. Sensor port blocked with carbon (a sensor that should be reading boost can't because the port is gunked up)
- 5. Genuinely low boost from a separate fault, the sensor is reading truthfully but the turbo isn't producing pressure
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read live data on commanded vs actual boost throughout the rev range; if both show similar low values, the turbo is the issue; if commanded climbs but actual stays low, the sensor or wiring is the issue
- 2. Inspect sensor for oil contamination, this is common on cars with leaking turbo seals
- 3. Check connector and wiring for damage or shorts to ground
- 4. Test sensor electrically against spec at known reference pressures
- 5. If wiring and sensor are healthy, look upstream at the turbo itself
Common questions about P0237
Difference between P0237 and P0299? +
P0237 is specifically the sensor reading low (sensor or wiring fault). P0299 is the system underboost (turbo not producing enough pressure). They can appear together if the sensor is masking a real underboost condition. Look at live data: if commanded boost rises but actual stays low and the sensor reading is also low, both faults are likely in play.
Could a recent service have caused this? +
Sometimes. After turbo replacement or boost system work, the sensor may have been disturbed or installed with a damaged connector. If P0237 appeared shortly after a workshop visit, check the sensor connector first, common installation issue.
Will a remap fix this? +
No, and it could make it worse. A remap doesn't fix a faulty sensor or a damaged turbo. If the underlying issue is a failed sensor, the new tune will work from incorrect data and may push the engine harder than it should. Diagnose and fix the fault before considering performance modifications.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →