What it means
The bank 1 sensor 2 NOx sensor heater sense circuit signal is above the expected range. 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 reports heater-related electrical information to the control module. This code sets when the sense signal is higher than expected; an open signal line or a connection to battery power can produce that reading, but the code alone does not identify the cause.
Common causes
Most likely first.
- Open signal line
- 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
- Save freeze-frame data and check related codes to determine whether the Bank 1 Sensor 2 heater sense fault is isolated.
- With the exhaust cool, inspect the connector and harness for corrosion, pin damage, an open-looking wire, or a pinched wire touching battery power.
- Check connector terminals for looseness, corrosion, or damage that could interrupt the signal.
- Use the wiring diagram to check sense-wire continuity and test for an unintended connection to battery power, following the manufacturer's isolation procedure.
- If the wiring and connector pass, test the heater sense circuit and sensor according to the manufacturer's diagnostic procedure.
Common fixes
- Repair an open Bank 1 Sensor 2 heater sense wire or damaged harness section.
- Repair wiring pinched against a battery-powered circuit.
- Clean or replace corroded or damaged connector terminals.
- Replace the Bank 1 Sensor 2 NOx sensor if it fails the specified sense circuit tests.
Can I keep driving?
If the vehicle runs normally, a short trip to arrange diagnosis is generally reasonable, but do not ignore the emissions warning. An AdBlue/DEF warning or no-start countdown may develop, and emissions inspection may be affected.
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.