Powertrain, generic (extended)

P2B0C Cold Start Cylinder 5 Injection Pulse Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

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)

Symptoms

  • Check engine light after two cold-start trips
  • Usually unremarkable running once warm, maybe a short rough idle when cold

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–1,000
Time0.3–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injector cylinder 5injector wiringengine control module

Related codes

P2B04P2B0BP2B0DP2B95P0205P0305

References: law.cornell.edu, gsi.ext.gm.com.