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EmissionsSeverity Medium: diagnose soon

P0137O2 Sensor Circuit Low Voltage (bank 1 sensor 2)

What it means

The oxygen sensor bank 1 sensor 2 stays at a low voltage (lean reading) for too long. The downstream sensor (after the catalyst) is mainly used to check how well the catalyst works.

Symptoms

  • Check engine light
  • Usually no change in how the car drives
  • Catalyst monitor may not complete

Common causes

  • Real lean condition (vacuum leak, low fuel pressure)
  • Exhaust leak upstream of the sensor drawing in air
  • Signal wire shorted to ground
  • Failed sensor

What to check first

  1. Check fuel trims: if they are high, look for the cause of the lean mixture first
  2. Propane-enrich the intake: a good sensor goes above 0.8 V
  3. Check for exhaust leaks and the sensor wiring
Can I drive with P0137? 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.

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P0137: questions and answers

What does P0137 mean?

P0137: O2 Sensor Circuit Low Voltage (bank 1 sensor 2). The oxygen sensor bank 1 sensor 2 stays at a low voltage (lean reading) for too long. The downstream sensor (after the catalyst) is mainly used to check how well the catalyst works.

What are the symptoms of P0137?

Check engine light. Usually no change in how the car drives. Catalyst monitor may not complete.

What causes P0137?

Real lean condition (vacuum leak, low fuel pressure). Exhaust leak upstream of the sensor drawing in air. Signal wire shorted to ground. Failed sensor.

How do you diagnose P0137?

1. Check fuel trims: if they are high, look for the cause of the lean mixture first 2. Propane-enrich the intake: a good sensor goes above 0.8 V 3. Check for exhaust leaks and the sensor wiring

Can I drive with P0137?

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