P2202: NOx Sensor Circuit Low (Bank 1 Sensor 1)

P2202 means the raw NOx value sent by the upstream sensor on bank 1 has dropped below the lowest figure a working sensor can report. Since the probe talks over CAN, the check concerns the transmitted value rather than a wire voltage. GM's Duramax diesels (6.6L LML and 3.0L LZ0) use a limit of minus 90 ppm, the LZ0 as Type B after two trips with dew point reached and supply in range; VW's 2014 Touareg TDI uses minus 105 ppm. GM bulletin 24-NA-094 lists P2202 among codes cured by an LZ0 software update on 2024 Silverado and Sierra 1500 pickups. A clearly negative value usually points to a drifting element or an internal sensor error. P2203 is the upper limit; P22A0 the same for sensor 2.

Medium severity. Can I keep driving?You can usually keep driving in the short term, but get it repaired soon: on many diesels, the warning eventually limits starting or engine power.

Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.

Symptoms

Malfunction indicator lamp on
Live data shows a negative NOx value upstream
SCR dosing may switch to a fallback strategy

Most likely causes

NOx sensing element drifted low or internally faulty
Engine software anomaly (GM 3.0L LZ0 2024, bulletin 24-NA-094)
Damaged probe lead or connector between element and sensor module

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes and the NOx data before and after the SCR catalyst
With the connector unplugged, check whether the signal wire is making contact with ground.
Check the sensor's connector and wiring
Look for exhaust leaks ahead of the sensor
Confirm that the AdBlue/DEF is of good quality
Replace the sensor only after ruling out power, ground, and leaks

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P2202 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
2: Fuel injection
02: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2202?

You can usually keep driving in the short term, but get it repaired soon: on many diesels, the warning eventually limits starting or engine power.

What causes code P2202?

The most common causes are: nOx sensing element drifted low or internally faulty; engine software anomaly (GM 3.0L LZ0 2024, bulletin 24-NA-094); damaged probe lead or connector between element and sensor module.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.