P22B6 code meaning
O2 Sensor Pumping Current Trim Circuit Low (Bank 1 Sensor 2)
Powertrain system Generic code P22xx codes Check engine light
What P22B6 means
By its name P22B6 is the low fault on the trim line of the bank 1 downstream wide-band probe, i.e. the lead to the calibration resistor in a Bosch-style sensor connector. GM's diesel tables use the slot differently: they set it when the oxygen value reported by the second NOx sensor falls below its physical minimum, less than -4 % in 200 of 250 samples in the 2016 table, with the engine in combustion mode and no NOx sensor fault pending. It is a Type B code with two trips. GM also lists P22B6 in PIP5468 for 2017-2018 Silverado/Sierra HD with the 6.6 L5P, where leaking charge-air ducting can set it, and in 21-NA-149 for the 3.0 LM2. P22B5 is the open, P22B7 the high counterpart, P22C3 bank 2. The lamp comes on.
P22B6 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P22B6
- Check engine light
- Negative oxygen percentage shown for the downstream sensor in live data
- Possible additional boost or air-flow codes when charge air leaks
Common causes of P22B6
- PossibleFaulty downstream NOx/oxygen sensor delivering an impossible oxygen value
- PossibleLeaking charge-air cooler ducting (GM 6.6 L5P)
- PossibleTrim or signal wire shorted to ground in the harness
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor bank1 sensor2Nox sensorOxygen sensor wiringECM
What each part of P22B6 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). |
| B6 | The exact fault in that area. |
What to do next
- Note P22B6 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 P22B6
What does P22B6 mean?
P22B6 means "O2 Sensor Pumping Current Trim Circuit Low (Bank 1 Sensor 2)". By its name P22B6 is the low fault on the trim line of the bank 1 downstream wide-band probe, i.e. It is a generic code, so it means the same on every make.
Is it safe to drive with P22B6?
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 P22B6 fail an emissions test?
Yes, it can. P22B6 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 P22B6 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P22B6 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.