Powertrain, generic (extended)

P22AC O2 Sensor Positive Current Control Circuit Low (Bank 1 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P22AC means the pump-current (positive current) line of the bank 1 downstream wide-band probe reads below its allowed window, usually because the wire touches ground or its insulation has worn through. GM includes the code in bulletin 21-NA-149 for 2019-2022 light-duty trucks and SUVs with the 3.0 Duramax LM2, where chafed engine wiring triggers a long list of faults; no public GM table gives a threshold. Not every maker uses this slot: Ford books a shorted lead on its upstream wide-band probes as P0131. Saab rates the upstream analog P2238 as a Type B fault. P22AB is the open-circuit case, P22AD the high one, P22B9 the bank 2 copy. Expect a lit warning lamp and stalled emission monitors rather than a change in driving.

Likely causes

Pump-current wire chafed against the body or exhaust and shorted to ground
Internal short in the downstream wide-band sensor
Water or contamination bridging the connector pins

Symptoms

  • Check engine light
  • Downstream oxygen value pinned at an extreme in live data
  • Possible failed emissions inspection because monitors are not ready

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–450
Time0.5–2.5 h

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

Parts involved

oxygen sensor bank1 sensor2oxygen sensor wiringecm

Related codes

P22ABP22ADP22B9P2238P22B3

References: static.nhtsa.gov, saabwisonline.com, newtonnet.co.uk, bosch-motorsport.com.