P22AC code meaning
O2 Sensor Positive Current Control Circuit Low (Bank 1 Sensor 2)
Powertrain system Generic code P22xx codes Check engine light
What P22AC means
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.
P22AC at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P22AC
- Check engine light
- Downstream oxygen value pinned at an extreme in live data
- Possible failed emissions inspection because monitors are not ready
Common causes of P22AC
- Most likelyPump-current wire chafed against the body or exhaust and shorted to ground
- PossibleInternal short in the downstream wide-band sensor
- Less likelyWater or contamination bridging the connector pins
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor bank1 sensor2Oxygen sensor wiringECM
What each part of P22AC means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 2 | Area: fuel and air metering (injector circuit). |
| AC | The exact fault in that area. |
What to do next
- Note P22AC and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P22AC
What does P22AC mean?
P22AC means "O2 Sensor Positive Current Control Circuit Low (Bank 1 Sensor 2)". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P22AC?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P22AC fail an emissions test?
Yes, it can. P22AC is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P22AC to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P22AC clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.