What it means
The boost pressure A signal voltage is below the lower diagnostic threshold — open circuit, short to ground, or sensor element failure.
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 measures pressure in the turbocharger or supercharger air path and sends a signal to the control module. P0237 sets when that signal falls below the module’s lower electrical threshold, which can result from an open circuit, a short to ground, or a failed sensor.
Common causes
Most likely first.
- Sensor circuit shorted to ground or open
- Boost pressure sensor failed
- Connector pins corroded - high contact resistance
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 data for boost sensor A; compare its reading with other pressure readings under the same conditions.
- Inspect sensor A’s connector and harness for corrosion, pushed-back pins, broken wires, or insulation rubbed through against ground.
- Using the wiring diagram, check the sensor’s reference, ground, and signal circuit for an open or short to ground.
- With the circuit isolated as required, test continuity through the signal wire and check for unwanted continuity to ground against the manufacturer’s specification.
- If the wiring and supply circuits are sound, test or substitute sensor A only as directed by the manufacturer’s diagnostic procedure.
Common fixes
- Clean and secure a corroded or loose sensor A connector.
- Repair an open wire or insulation damage that shorts the signal to ground.
- Replace boost pressure sensor A if it fails the specified circuit test.
- Repair a module fault only after the sensor circuit has been verified.
Can I keep driving?
If power is reduced or limp mode is active, avoid hard acceleration, towing, and high-speed driving because the module may not be receiving a reliable boost signal. Stop if the engine smokes heavily, runs roughly, or cannot maintain a safe speed.
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.