P22AC: 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. 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.

Medium severity. Can I keep driving?Yes, you can normally drive in moderation, but get it repaired soon: you will use more fuel and the catalytic converter can be damaged over time.

Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank. Sensor 2 is the sensor after the catalytic converter.

Symptoms

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

Most 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

What to check, in order

Start with the simplest. You can tick off each step.

Check the wiring and connector of the sensor indicated
With the connector unplugged, check whether the signal wire is making contact with ground.
Look for exhaust leaks
Check the signal in live data with the engine warm
Check the fuse and the heater resistance if the code mentions it
Replace the sensor if it has power and does not respond

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P22AC means

P: Powertrain: engine and transmission
2: Generic code: same on every make
2: Fuel injection
AC: Specific fault in that system

Frequently asked questions

Can I keep driving with code P22AC?

Yes, you can normally drive in moderation, but get it repaired soon: you will use more fuel and the catalytic converter can be damaged over time.

What causes code P22AC?

The most common causes are: 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.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.