Powertrain, generic (extended)

P2212 NOx Sensor Heater Sense Circuit Intermittent (Bank 1 Sensor 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

Besides driving the heater, the upstream NOx sensor on bank 1 has a sense path that reports back how the heater actually responds; GM measures heater resistance on a separate HTemp pin. P2212 means this feedback keeps dropping out or jumping instead of failing for good. No manufacturer publishes thresholds for P2212; GM's 3.0L LZ0 tables cover only the steady cases (P2208 open, P2210 short to ground, P2211 short to power). CARB requires heater circuit faults that contradict the commanded state to be caught. Typical causes are a loose contact or cracked lead that opens with heat or vibration. P2209 is a plausible but poor heater response; P2205-P2207 concern the control side. The MIL may come and go.

Likely causes

Loose or corroded contact in the NOx sensor connector
Cracked conductor in the probe lead that opens with heat or vibration
Intermittent fault in the sensor module's heater measurement

Symptoms

  • Malfunction indicator lamp on, possibly intermittent
  • Upstream NOx value briefly invalid

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–900
Time0.5–3 h

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

Parts involved

nox sensornox sensor heaternox sensor wiring

Related codes

P2208P2209P2210P2211P2205P2204

References: law.cornell.edu, gsi.ext.gm.com, ni.com.