P0168 low

O2 Sensor Heater Circuit High Voltage (Bank 2, Sensor 3)

The P0168 code means the vehicle's onboard diagnostic system has detected: O2 Sensor Heater Circuit High Voltage (Bank 2, Sensor 3). This is a low severity code.

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Keep driving?: Yes, but fix soon
DIY difficulty: easy
Estimated cost: $80 - $300 (parts and labor)

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Common Symptoms

Check Engine Light on
No driveability symptoms typically
Emissions monitors may not complete
Possible blown fuse affecting multiple sensors

Probable Causes (Ranked by Likelihood)

O2 sensor heater shorted internally Very High
Wiring short to battery voltage on ground side High
Corroded heater connector Moderate
PCM heater control issue Low

Step-by-Step Diagnostic Procedure

Measure O2 sensor heater resistance. Very low resistance (below 2 ohms) indicates internal short.
Check heater ground circuit for proper continuity to ground.
Inspect wiring for damage or shorts to voltage.
Replace sensor if heater resistance is out of spec.

Frequently Asked Questions

What does heater circuit high voltage mean?

The PCM detects higher voltage than expected on the heater ground circuit, usually from a short or high resistance in the ground path.

Can a shorted heater blow a fuse?

Yes, a shorted O2 sensor heater can blow the heater fuse, which may affect other O2 sensors on the same circuit.

Is this code urgent?

No, P0168 is low severity. The sensor will still function once warmed by exhaust heat. Repair at your convenience but before your next emissions test.