Powertrain, generic (extended)

P2C64 O2 Sensor Pumping Current Trim Circuit High Bank 1 Sensor 3

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2C64 is the high-side partner of P2C63: the oxygen reading attributed to sensor 3 of bank 1 climbs above what the probe can physically deliver. On GM's 3.0L Duramax diesel the value comes from NOx sensor 3 behind the second catalyst, and table 25OBDG04B sets the code once that O2 reading exceeds 29 percent, clearly more than the roughly 21 percent of fresh air, in 100 of 200 samples under the same enable conditions as the low check; Type B, MIL after two trips. Such a figure hints at a signal fault in the sensor or its wiring rather than real exhaust oxygen. The harness bulletins PIT5751C and 21-NA-149 for 2020-21 GM models with the 3.0L LM2 list P2C64 as well. P2C62 is the open circuit, P23AF the NOx circuit high code of the same sensor.

Likely causes

Third exhaust sensor (on GM diesels NOx sensor 3) delivering an implausibly high O2 value
Engine harness chafed or shorted (GM 3.0L LM2, PIT5751C)
Moisture or corrosion in the sensor connector

Symptoms

  • MIL on after two trips
  • Further NOx sensor or aftertreatment codes stored

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–600
Time0.5–3 h

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

Parts involved

oxygen sensor b1s3nox sensoroxygen sensor wiringecm

Related codes

P2C62P2C63P2C65P23AFP2628

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