What it means
The bank 1 sensor 2 NOx sensor heater sense circuit signal is intermittent. The code alone does not identify the cause.
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 after the engine’s first cylinder bank, and its heater sense circuit lets the control module monitor heater behavior. This code sets when the circuit signal cuts in and out rather than staying consistent, often because a connector or harness connection is disturbed by 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
- Save freeze-frame data and check when the fault occurred, then monitor Bank 1 Sensor 2 heater sense data for dropouts if the scan tool supports it.
- With the exhaust cool, inspect the sensor connector for loose fit, corrosion, damaged pins, or signs that vibration has disturbed the connection.
- Follow the harness from Bank 1 Sensor 2 and look for rubbing, tension, or contact with a vibrating component.
- Check circuit continuity and connector contact while gently moving the harness, using the manufacturer's procedure to avoid damaging terminals.
- If no wiring or connector interruption is found, test the sensor heater sense circuit for intermittent failure as specified by the manufacturer.
Common fixes
- Secure the Bank 1 Sensor 2 harness away from vibration, rubbing, and heat.
- Repair a loose, corroded, or intermittently contacting connector terminal.
- Replace a harness section damaged by rubbing or vibration.
- Replace the Bank 1 Sensor 2 NOx sensor if its heater sense circuit fails the specified intermittent fault checks.
Can I keep driving?
If the vehicle runs normally, a short drive for diagnosis is generally reasonable, but the warning may return as vibration or temperature changes. The emissions system may be unable to verify NOx control, and an AdBlue/DEF warning or no-start countdown may follow.
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.