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.
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
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.
What actually makes the computer set an oxygen sensor code?
The OBD II regulation requires four separate detections for an oxygen sensor (Title 13 CCR 1968.2, section (e)(7.2)): deterioration in voltage, response rate or amplitude that would push emissions past 1.5 times the FTP standards; loss of circuit continuity; out-of-range values; and the case where the sensor has degraded enough that the fuel system stops using it and falls back to open loop. A sensor can therefore set a code while still producing a signal that looks plausible on a scan tool. This is the threshold the monitor is designed around, not a description of your specific fault — the regulation says what the system must detect, not how to find it on your vehicle.
Mechanics Guide Step-by-step diagnosis
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).
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Check wiring for shorts to voltage source.
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Verify upstream fuel trim is normal. If Bank 2 is running very rich, the sensor may be reading correctly.
Sources 3
This page is built from documented references. Verify against your own service info before repair work.
- California Code of Regulations, Title 13 section 1968.2 (OBD II)malfunction criteria, section (e)
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- 2010-2020 Ram 2500 (6.4L HEMI)
- 2012-2019 Toyota 4Runner (4.0L V6)
- 2008-2018 Nissan Titan (5.6L V8)
- 2011-2020 Ford Expedition (3.5L EcoBoost)
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