P0164 — O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)
Drive with caution — fix soon.
What P0164 means
This code is set when the voltage signal from the bank 2 sensor 3 oxygen sensor stays too low, which can indicate the sensor reads a constant lean exhaust or that there's a short or open in the circuit. This rear sensor helps monitor emissions and catalytic converter efficiency. It's commonly fixed by replacing the oxygen sensor, though wiring shorts, bad connectors, or a true lean fuel condition should be ruled out first.
Common symptoms
- Check engine light is on
- Slightly reduced fuel economy
- Failed emissions or smog test
- Possible rough idle if a lean condition is present
- Low or flat oxygen sensor voltage on a scan tool
Common causes
- Faulty bank 2 sensor 3 oxygen sensor
- Short to ground in the sensor signal wiring
- Corroded or loose sensor connector
- Lean exhaust condition from an air or vacuum leak
- Exhaust leak near the sensor location
Typical repair cost
$150 – $400
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0164 code?
In most cases yes, at least for short trips, since this sensor mainly affects emissions monitoring. If you also notice rough idling or hesitation, a lean condition could be involved and you should get it looked at sooner. Otherwise, plan a diagnosis within a week or two.
How much does it cost to fix a P0164 code?
Typical repairs run $150 to $400, mostly for the oxygen sensor and about an hour of labor. If the cause is a wiring short or an air leak rather than the sensor, the price can vary. Diagnosis time is well spent here to avoid replacing a good sensor.
Is a P0164 code serious?
It's usually a moderate concern. The car stays drivable, but if a genuine lean condition is behind the low voltage, it's worth addressing before it affects performance or the catalytic converter. At minimum it will keep you from passing an emissions test.
Does low voltage mean the engine is running lean?
It can, but not always. A low oxygen sensor voltage often reflects a lean exhaust, yet the same reading can also come from a shorted wire or a failing sensor. That's why a technician checks fuel trims and wiring before deciding whether the sensor or the fuel mixture is the real problem.