O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
What does P0158 mean?
The P0158 code means the vehicle's onboard diagnostic system has detected: O2 Sensor Circuit High Voltage (Bank 2 Sensor 2). This is a low severity code.
Common Symptoms
- Check Engine Light on
- No significant drivability issues
- Slightly increased emissions
- Catalyst monitoring may not complete
- Possible emissions test failure
Probable Causes (Ranked by Likelihood)
- Failed downstream O2 sensor stuck reading rich Very High
- Short to power in the sensor signal wiring High
- Contaminated sensor from oil or coolant Moderate
- Corroded connector causing signal interference Moderate
- Failing catalytic converter on bank 2 Low
Step-by-Step Diagnostic Procedure
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Monitor bank 2 sensor 2 voltage on a scan tool. A fixed high reading (above 0.8V) indicates a rich condition or failed sensor.
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Disconnect the sensor and check if the voltage drops. If it does, the sensor is at fault. If it remains high, check for a wiring short to power.
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Inspect the sensor for contamination -- white residue (coolant) or oily deposits (burning oil).
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Check the wiring for shorts to other power circuits or for chafed insulation.
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Verify the connector is clean and free of moisture.
Frequently Asked Questions
Can I drive with code P0158?
Yes, you can drive normally. The downstream sensor on bank 2 is a monitoring sensor only and does not control fuel delivery.
What causes high voltage on a downstream O2 sensor?
High voltage means the sensor is detecting a rich exhaust condition after the catalytic converter. This is usually caused by a failed sensor, a contaminated sensing element, or in rare cases a failing catalytic converter that is not properly oxidizing exhaust gases.
Is P0158 the bank 2 version of P0138?
Yes. P0138 is high voltage on bank 1 sensor 2, and P0158 is the same fault on bank 2 sensor 2.