O2 Sensor Circuit High Voltage (Bank 2, Sensor 3)
The P0164 code means the vehicle's onboard diagnostic system has detected: O2 Sensor Circuit High Voltage (Bank 2, Sensor 3). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $100 - $350 (parts and labor)
Test O2 sensor voltage (should fluctuate 0.1-0.9V). Do not replace a $150 sensor without confirming it is actually bad first.
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Shows real-time O2 sensor readings on your phone. See if the sensor is lazy, stuck, or actually working before spending money.
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Common Symptoms
- Check Engine Light on
- Rich exhaust smell
- Decreased fuel economy
- Black smoke from exhaust in severe cases
Probable Causes (Ranked by Likelihood)
- Failed O2 sensor stuck rich (Bank 2, Sensor 3) Very High
- Contaminated sensor from coolant or silicone High
- Wiring short to battery voltage Moderate
- Fuel system running excessively rich Low
Step-by-Step Diagnostic Procedure
-
Read Bank 2 Sensor 3 voltage. Constant reading above 0.8V indicates a stuck rich sensor.
-
Inspect sensor for contamination (white deposits indicate coolant, dark oily deposits indicate oil).
-
Check wiring for shorts to voltage source.
-
Verify upstream fuel trim is normal. If Bank 2 is running very rich, the sensor may be reading correctly.
Frequently Asked Questions
What does high voltage mean on an O2 sensor?
High voltage (above 0.8V stuck) means the sensor reports a rich condition from a failed sensor, contamination, or an actual rich fuel mixture.
Can coolant contamination cause P0164?
Yes, a leaking head gasket or intake manifold gasket can allow coolant to reach the O2 sensor. White powdery deposits on the sensor tip are a telltale sign.
How often should O2 sensors be replaced?
Original O2 sensors typically last 60,000-100,000 miles. Replace only when diagnosed as faulty.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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