P2B04Cylinder 5 Injection Pulse Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2B04 extends the warm-running missed-pulse check to cylinder 5, so it only matters on engines with five or more cylinders. No manufacturer documents P2B04 publicly as a monitor of its own. Among GM's 2025 V8 documents it turns up solely inside code lists attached to common calibration maps; the main entries there are the cold-start codes P2B08–P2B0F, while warm small-pulse faults of each cylinder go to GM's own offset-learning codes (P10AB/P10AC for cylinder 5). Where it is used, the idea follows the CARB rule that output parts need a functional check: the controller verifies the injector really opened on command. Which physical cylinder carries number 5 depends on the maker's numbering scheme, so check the engine's layout before pulling parts. Cold-start faults here are P2B0C.
- What you may notice
- Engine warning lamp on
- Rough running or misfire on cylinder 5 (P0305)
- Likely causes
- LikelyCylinder 5 injector sticking or opening too slowly
- PossibleChafed or high-resistance wiring to injector 5
- RareCalibration error in the engine software
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €1,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.