What it means
The ECU detects abnormally low voltage from the third O2 sensor on bank 2. Indicates lean exhaust, open sensor or wiring shorted to ground.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 2 Sensor 3 is the third oxygen sensor in the bank 2 exhaust path on vehicles that have one. P0164 sets when the ECU sees a signal voltage that is too low, which can reflect lean exhaust, a failed sensor, or a signal circuit pulled toward ground.
Common causes
Most likely first.
- Lean exhaust condition
- O2 sensor failed
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
How to diagnose it
- Read freeze-frame and live data to verify that Bank 2 Sensor 3 remains unusually low during the conditions that set the code.
- Inspect the sensor connector for corrosion or damaged pins and check the signal wire for contact with ground or exhaust damage.
- Look for exhaust leaks or engine conditions that could make the bank 2 exhaust genuinely lean.
- Check related live fuel-trim and oxygen-sensor data to distinguish a lean exhaust condition from an electrical signal fault.
- Test the sensor signal and circuit against the manufacturer's specification before replacing Bank 2 Sensor 3.
Common fixes
- Repair corroded connector pins or a poor connection at Bank 2 Sensor 3.
- Repair a signal wire shorted to ground or otherwise damaged.
- Repair an exhaust leak or confirmed engine condition causing lean exhaust.
- Replace Bank 2 Sensor 3 if its output is low despite a sound circuit and no confirmed lean condition.
Can I keep driving?
A low signal may reflect a real lean condition, so avoid heavy acceleration if the engine is running poorly. The fault can raise emissions and fuel use; have it checked promptly if rough running or hesitation is present.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.