What Does P0163 Mean?
The oxygen sensor on bank 2, sensor 3 is reporting a voltage below the expected minimum threshold. Sensor 3 is typically a third O2 sensor found on vehicles with dual catalytic converters or extended exhaust monitoring. A persistent low voltage (below ~0.1V) suggests the sensor is biased lean or has an electrical issue. The driver may notice a check engine light and potential fuel economy changes.
Common Causes
40%
Failed O2 sensor with a shorted or degraded sensing element
25%
Exhaust leak upstream of the sensor causing excess oxygen to reach it
20%
Open or high-resistance signal wire between the sensor and ECM
10%
Short to ground in the O2 sensor signal circuit
5%
ECM signal input circuit failure
Diagnostic Steps
1
Monitor live data for bank 2 sensor 3 voltage. A healthy sensor at operating temperature should show some switching activity or a steady reading appropriate for the location. A stuck-low reading near 0V is abnormal.
2
Inspect the sensor wiring and connector for damage, corrosion, or water intrusion. Look for melted insulation from exhaust heat exposure.
3
Disconnect the sensor and measure the signal wire resistance from the ECM connector to the sensor connector. It should be less than 5 ohms with no continuity to ground.
4
Perform a propane enrichment test or snap-throttle test to see if the sensor voltage rises. If it does not respond at all, the sensor is likely failed internally.
5
Check for exhaust leaks between the catalytic converter outlet and the sensor location using a smoke machine or by listening for hissing during idle.
Estimated Repair Cost
$150 - $400
Parts + labor, varies by vehicle and location
The oxygen sensor on bank 2, sensor 3 is reporting a voltage below the expected minimum threshold. Sensor 3 is typically a third O2 sensor found on vehicles with dual catalytic converters or extended exhaust monitoring. A persistent low voltage (below ~0.1V) suggests the sensor is biased lean or has...
The most common cause of P0163 (02 Sensor Circuit Low Voltage (Bank 2 Sensor 3)) is: Failed O2 sensor with a shorted or degraded sensing element
Typical repair costs for P0163 range from $150 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving. Sensor 3 is typically a monitoring sensor and does not directly affect fuel trim. However, catalyst efficiency monitoring will be compromised and the vehicle will fail emissions testing.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0163 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System / Emissions
Difficulty
Type
Generic (SAE)
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