P2204
NOx Sensor Circuit Intermittent Bank 1 Sensor 1
NOx / SCR emissions
Generic OBD-II
Medium
What it means
P2204 means the ECM sees an intermittent or erratic signal from the bank 1, sensor 1 NOx sensor, part of the diesel SCR/emissions system that measures nitrogen-oxide output. It's mainly an emissions fault, though some diesels reduce power if it persists. The usual cause is the NOx sensor itself or an intermittent wiring or connector fault in its circuit.
Medium
Can I keep driving? Usually driveable, but on diesels a NOx-sensor fault can trigger reduced power or a DEF/SCR warning, so get it checked to avoid a derate.
Common symptoms
What you'll notice
- Check-engine light on
- Possible reduced power or SCR/DEF warning (diesels)
- Failed emissions test or incomplete readiness monitor
- Higher NOx emissions
Common causes
Most likely first
- Faulty NOx sensor (bank 1, sensor 1)Likely
- Intermittent open, short, or chafed wiring in the NOx sensor circuitCommon
- Poor or corroded connector at the sensorCommon
- Exhaust leak near the sensorLess often
- NOx sensor module or PCM fault (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data, then wiggle-test and inspect the NOx sensor connector and wiring for intermittent faults.
- Check for exhaust leaks near the sensor.
- Inspect the sensor and its module for damage or corrosion.
- Replace the NOx sensor if the wiring checks out.
- Clear the code and retest.
FAQ
Quick answers
Is it safe to drive with P2204?+
Usually yes short-term, but it's mainly an emissions fault and some diesels reduce power or warn on the SCR/DEF system if it persists. Have it diagnosed before it forces a derate.
Can I just clear P2204?+
You can, but an intermittent fault will set it again. Find the loose connection or failing sensor first.
Related codes
Often seen with P2204
Read & clear P2204 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX