O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)

Where it lives

For P0137, the sensor sits on the circuit this code reports. The description of P0137 puts it on bank 1.

Check these first

• Exhaust leak before the downstream sensor
• Failed downstream oxygen sensor
• Open or shorted sensor wiring
• Controller ground issue

What to do next

1. Check for exhaust leaks and verify the sensor's ground
2. Watch for a reading pinned near 0v at steady throttle
3. Test the signal circuit continuity
4. Replace the sensor if it reads low with a known-good exhaust seal
5. Clear the code and verify the catalyst monitor resets

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