NOx Sensor Circuit Low Bank 1 Sensor 1
What it means
P2202 means the bank 1, sensor 1 NOx sensor circuit is reading below its expected voltage range. This sensor measures nitrogen-oxide levels so the emissions system (including SCR/DEF on diesels) can keep exhaust clean. A low signal usually means a failing sensor, a wiring short, or a bad connection. The engine typically still runs, but emissions rise and some vehicles limit power until it's fixed.
Can I keep driving? Usually driveable, but it's an emissions fault — some vehicles limit power or raise DEF warnings, and it will fail emissions testing, so repair before long trips.
Common symptoms
What you'll notice
- Check-engine light on
- Increased NOx emissions / emissions-test failure
- Possible SCR/DEF warning message on diesels
- Possible reduced-power or derate mode on some vehicles
Common causes
Most likely first
- Faulty NOx sensor (bank 1, sensor 1)Likely
- Open or shorted wiring in the NOx sensor circuitCommon
- Poor or corroded connector at the sensorCommon
- Exhaust leak near the sensor affecting its readingLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the NOx sensor connector and wiring for damage, corrosion, or a short to ground.
- Check the sensor's supply, ground, and signal against spec.
- Inspect for exhaust leaks upstream of the sensor that could skew readings.
- Replace the NOx sensor if the circuit reads low with confirmed-good wiring.
FAQ
Quick answers
Is it safe to drive with P2202?+
Can I just clear P2202?+
Related codes
Often seen with P2202
Read & clear P2202 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.