P2C63 code meaning
O2 Sensor Pumping Current Trim Circuit Low Bank 1 Sensor 3
Powertrain system Generic code P2Cxx codes Check engine light
What P2C63 means
P2C63 reports that the oxygen value from the third exhaust sensor of bank 1 has dropped below its physically possible minimum. Despite the trim wording, GM uses it on the 3.0L Duramax diesel for the O2 signal of NOx sensor 3, which sits behind the second catalyst: table 25OBDG04B (2025) fails a reading under -6 percent in 100 of 200 samples on a 25 ms task, with the engine running, supply above 11 V and the sensor ready; Type B, MIL after two trips. GM's PIT5751C and bulletin 21-NA-149 name P2C63 among many codes on 2020-21 Silverado, Sierra, Tahoe, Yukon and Escalade with the 3.0L LM2; the cause was an engine harness rubbed through above the generator or shorted against the clamp of the crankcase-pressure-regulator hose. P2C64 is the high side, P23AE the NOx circuit low code of this sensor.
P2C63 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2C63
- MIL on after two trips
- On the GM LM2 often many other codes, rough running or blown fuses when the harness is damaged
- Aftertreatment monitors not completing
Common causes of P2C63
- Most likelyEngine harness chafed or shorted (GM 3.0L LM2 - at the generator or the crankcase pressure regulator clamp)
- PossibleThird exhaust sensor (on GM diesels NOx sensor 3) reporting an implausibly low O2 value
- Less likelyCorroded or loose sensor connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor b1s3Nox sensorOxygen sensor wiringECM
What each part of P2C63 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| C | Area: hybrid propulsion. |
| 63 | The exact fault in that area. |
What to do next
- Note P2C63 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 P2C63
What does P2C63 mean?
P2C63 means "O2 Sensor Pumping Current Trim Circuit Low Bank 1 Sensor 3". P2C63 reports that the oxygen value from the third exhaust sensor of bank 1 has dropped below its physically possible minimum. It is a generic code, so it means the same on every make.
Is it safe to drive with P2C63?
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 P2C63 fail an emissions test?
Yes, it can. P2C63 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 P2C63 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P2C63 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.