What it means
The bank 1 sensor 2 NOx sensor circuit signal is intermittent. The code does not by itself identify whether the cause is the sensor, its wiring, or its connections.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 sensor 2 is the downstream NOx sensor, and its circuit sends readings to the control module. This code sets when that signal drops out or changes inconsistently, often because a connector or harness connection loses contact with vibration.
Common causes
Most likely first.
- Intermittent connector
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Review freeze-frame data and code status to determine whether the bank 1 sensor 2 fault is current or intermittent.
- Inspect the sensor connector and harness routing for loose retention, chafing, or contact with a vibrating or hot component.
- Check connector terminals for corrosion, pin damage, or poor fit that could make contact intermittent.
- Monitor live NOx data while gently moving the accessible harness and connector to see whether the signal cuts out.
- If the interruption is not visible, test circuit continuity and connections under the manufacturer's diagnostic procedure.
Common fixes
- Secure the harness away from vibrating, hot, or abrasive parts.
- Repair loose, corroded, or damaged connector terminals.
- Repair an intermittent wire inside the harness.
- Replace bank 1 sensor 2 if its signal remains intermittent with a verified circuit.
Can I keep driving?
If the vehicle runs normally, cautious short trips are usually possible, but the NOx warning may return and emissions monitoring can be unreliable. Repair it soon because ignored emissions faults can lead to a DEF warning or start countdown.
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.