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P0237Turbocharger/Supercharger Boost Sensor "A" Circuit Low

What it means

The boost pressure sensor signal voltage is lower than the sensor can normally produce (usually below about 0.2 V on a 0–5 V sensor). Most often the signal wire is shorted to ground or the 5 V supply is missing.

Symptoms

  • Limp mode with low power
  • Black smoke or poor acceleration
  • Check engine light

Common causes

  • Signal wire shorted to ground or chafed through
  • 5 V reference open, or pulled down by another faulty sensor on the same supply
  • Failed boost pressure sensor
  • Water or corrosion in the connector

What to check first

  1. With the key on, measure the 5 V reference at the connector (about 4.8–5.1 V)
  2. Back-probe the signal and watch it while wiggling the harness
  3. Unplug sensors that share the 5 V reference one at a time and see whether the supply recovers
Can I drive with P0237? Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

How to test the parts behind P0237

MAP and boost pressure sensorWiring, typical values, multimeter and scope tests

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P0237: questions and answers

What does P0237 mean?

P0237: Turbocharger/Supercharger Boost Sensor "A" Circuit Low. The boost pressure sensor signal voltage is lower than the sensor can normally produce (usually below about 0.2 V on a 0–5 V sensor). Most often the signal wire is shorted to ground or the 5 V supply is missing.

What are the symptoms of P0237?

Limp mode with low power. Black smoke or poor acceleration. Check engine light.

What causes P0237?

Signal wire shorted to ground or chafed through. 5 V reference open, or pulled down by another faulty sensor on the same supply. Failed boost pressure sensor. Water or corrosion in the connector.

How do you diagnose P0237?

1. With the key on, measure the 5 V reference at the connector (about 4.8–5.1 V) 2. Back-probe the signal and watch it while wiggling the harness 3. Unplug sensors that share the 5 V reference one at a time and see whether the supply recovers

Can I drive with P0237?

Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.