P2204

NOx Sensor Circuit Intermittent Bank 1 Sensor 1

Q: 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.

Q: Can I just clear P2204?

You can, but an intermittent fault will set it again. Find the loose connection or failing sensor first.

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.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear P2204 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX