P2B0C flags cylinder 5 when its injector fails to show an opening signature on the split pulses used to heat the catalyst after a cold start. Publicly it is documented only by GM, in the 2025 V8 table 25OBDG06A, which lists the cold-start codes for all eight cylinders (P2B08–P2B0F): Type B, decision after 50 to 100 samples. For this engine GM's cold-start window is narrow – catalyst below 550 °C, coolant between 6 and 66 °C, 550–2,000 rpm, foot off the pedal (up to 1 %) and less than 100 s after start. No service bulletin naming P2B0C was found. The background is CARB's rule for model years 2026 to 2028 to check missing split pulses in the cold-start phase under separate codes. Warm-engine misses on cylinder 5 would be P2B04.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Cylinder 5 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Check engine light after two cold-start trips
- Usually unremarkable running once warm, maybe a short rough idle when cold
Most likely causes
- Cylinder 5 injector not lifting on the short cold-start pulses
- Injector 5 wiring or connector with a contact fault
- ECM calibration issue (check for software updates)
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P2B0C means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- B: Subsystem depends on the code range
- 0C: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2B0C?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P2B0C?
The most common causes are: cylinder 5 injector not lifting on the short cold-start pulses; injector 5 wiring or connector with a contact fault; eCM calibration issue (check for software updates).
Related codes
- P2B04Cylinder 5 Injection Pulse Performance
- P2B0BCold Start Cylinder 4 Injection Pulse Performance
- P2B0DCold Start Cylinder 6 Injection Pulse Performance
- P2B95Cold Start Injection Pulse Performance
- P0205Cylinder 5 Injector A Circuit/Open
- P0305Cylinder 5 Misfire Detected
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.