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

What does P2202 mean?

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.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

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

Common causes

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

Likelihood is a general estimate across vehicles; your make and model may differ.