P2202

NOx Sensor Circuit Low Bank 1 Sensor 1

Q: Is it safe to drive with P2202?

Often yes for normal driving, but it's an emissions fault and some diesels enter a reduced-power derate or start a DEF countdown, so don't ignore it.

Q: Can I just clear P2202?

It returns once the low circuit reading is seen again. The NOx sensor or its wiring must be repaired for the code to stay off.

Auxiliary emissions control Generic OBD-II Medium

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.

Medium

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.

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
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?+

Often yes for normal driving, but it's an emissions fault and some diesels enter a reduced-power derate or start a DEF countdown, so don't ignore it.

Can I just clear P2202?+

It returns once the low circuit reading is seen again. The NOx sensor or its wiring must be repaired for the code to stay off.

Read & clear P2202 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