P262BControl Module Power Off Timer 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
- P262B concerns the timer that keeps counting inside a control module while the vehicle is shut down, used to measure how long it has been off. GM runs two checks on it: a count-up test while run/crank is inactive, failing when two consecutive readings differ by over 1.5 s in 4 of 20 one-second samples, and a range test comparing the hardware timer with a mirror timer at shutdown or restart (deviation above 25 % in the 2014 tables). It is Type B, so the MIL follows on the second trip. GM saw false sets on 2019–2020 CT6 4.2 L engines when the engine cooled faster than expected, for example in wind or an air-conditioned garage (PIP5754: clear the code and keep the ECM), and links P262B to ECM supply or ground faults (PIP5609) and to a lost ignition relay feed (PIT5391).
- What you may notice
- MIL on after two drive cycles
- Possibly other control module codes stored at the same time
- Likely causes
- LikelyPoor ECM power or ground connection, momentary supply loss
- PossibleIgnition relay or its control circuit not supplying the module
- PossibleDiagnostic calibration too sensitive to fast engine cool-down
- RareInternal timer hardware fault in the control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €40 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.