What it means
The bank 1 sensor 2 NOx sensor heater control circuit is above the expected electrical range. The code does not by itself 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 brings the sensing element up to operating temperature. The control module monitors the heater control circuit; this code sets when that circuit reads higher electrically than expected, which can happen if it is shorted to battery power or has a connection fault.
Common causes
Most likely first.
- Short to B+
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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
- Use a scan tool to record freeze-frame data and check related codes, since supply or ground faults may affect more than the heater control circuit.
- With the exhaust cool, inspect the Bank 1 Sensor 2 connector and nearby harness for corrosion, pin damage, pinching, or contact with a powered wire.
- Check the connector for loose or backed-out terminals and corrosion that could raise contact resistance.
- Using the wiring diagram, test the heater control wire for an unintended connection to battery power, isolating the sensor and module as specified by the manufacturer.
- If the wiring checks pass, test the heater and control circuit against the manufacturer's diagnostic procedure before replacing the NOx sensor or considering a module fault.
Common fixes
- Repair a pinched or chafed Bank 1 Sensor 2 heater control wire that is contacting battery power.
- Clean or repair corroded connector terminals and restore a secure connection.
- Replace a damaged connector or harness section.
- Replace the Bank 1 Sensor 2 NOx sensor if its heater fails the specified tests.
Can I keep driving?
If the vehicle runs normally, a short trip to arrange diagnosis is generally reasonable, but avoid ignoring the warning or using the vehicle for extended driving. The emissions fault may trigger an AdBlue/DEF warning or a no-start countdown, and the vehicle may fail an emissions inspection.
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.