Powertrain, generic (extended)

P22A5 NOx Sensor Heater Control Circuit High (Bank 1 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P22A5 is the opposite of P22A4: the heater control line of the rear NOx sensor on bank 1 has a short to supply voltage. The sensor module then cannot switch or regulate the heater, and the element risks running too hot or the module shuts the heater off to protect it. GM describes the check on the 3.0L LZ0 as a battery short at the heater control pin, 80 failures in 160 samples with dew point reached and supply above 9.9 V, Type B after two trips; the 2017 small diesels test the H+ supply pin of the Gen 3.0 sensor with 20 failures in 40 samples. GM bulletin 24-NA-094 lists P22A5 among codes an LZ0 software update clears on 2024 pickups. No public bulletin names a hardware fix. P22A3 is the open circuit, P22A4 the ground short, P2207 the front sensor.

Likely causes

Heater circuit inside the sensor shorted to supply voltage
Probe lead or connector touching a powered conductor
Software anomaly (GM 3.0L LZ0 2024, bulletin 24-NA-094)

Symptoms

  • Malfunction indicator lamp on after two trips
  • Heater switched off, outlet NOx sensor not 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

P22A3P22A4P22A6P2207

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