P2B18Cylinder 5 Injection Pulse Offset Not Learned
- 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
- P2B18 means injector 5 has no learned offset. No manufacturer documents this exact code. On petrol direct injection GM covers a related idea with codes of its own: in the 2025 V8 table the ECM adds up the opening magnitude and closing time compensation of each injector, both derived from the feedback voltage, and P10AB or P10AC set for cylinder 5 when that sum is below the minimum or above the maximum limit (Type B, 50 to 100 samples). A not-learned status, by contrast, says that no usable value exists yet, for example after a new injector or control unit or after an adaption reset. For diesel engines CARB (f)(4.2.4)(A)(i) requires detection of feedback that does not start in time. The limit-exceeded twin is P2B19.
- What you may notice
- Warning lamp
- Rarely noticeable; at most slightly uneven low-load running
- Likely causes
- LikelyNew injector 5 or control unit without a completed learn
- PossibleEnabling conditions for the learn not met often enough
- RareFaulty injector 5 wiring preventing a valid measurement
- 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: €0 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.