Powertrain, generic (extended)

P22A3 NOx Sensor Heater Control Circuit/Open (Bank 1 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

The ceramic element of a NOx sensor measures only after its built-in heater has brought it to several hundred degrees. P22A3 reports a break on the heater control side of the rear sensor on bank 1, behind the SCR catalyst. GM's 6.6L LML sets it when the sensor reports an open heater over CAN longer than 10 s, Type A. On the 3.0L LZ0 the heater control pin is tested for a missing load (80 failures in 160 samples), on the 2017 small diesels the H+ supply pin of the Gen 3.0 sensor; both Type A, so the MIL comes on after one trip. Volvo and Mack read P22A3-13 as a probable outlet sensor failure, and GM bulletin 24-NA-094 lists the code for an LZ0 software update. P22A4 and P22A5 are shorts, P22A6 the heater sense line, P2205 the front sensor.

Likely causes

Heater element in the outlet NOx probe burnt through
Broken conductor between probe and sensor module
Software anomaly (GM 3.0L LZ0 2024, bulletin 24-NA-094)

Symptoms

  • Malfunction indicator lamp on after one trip
  • Outlet NOx sensor never reports ready
  • SCR warning on the display

Repair estimate

DifficultyMediumDIY possible
Parts and labour€150–1,000
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

nox sensornox sensor heater

Related codes

P22A4P22A5P22A6P220FP2205

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.