P254FEngine Hood Switch Circuit

How the car detects it: P254F concerns the circuit of the hood switch, which tells the control units whether the engine hood is open. Engines that can start on their own, such as in hybrids or stop/start systems, need this to block an automatic start while someone works under the hood. GM documents the code in the ECM section of its 2012 table 12OBDG06 for the two-mode hybrid Tahoe, Yukon, Escalade, Sierra and Silverado: the engine module reads two hood switch states, checks every 25 ms with run/crank voltage between 11 and 32 V, and sets the fault after 0.5 s as Type B, two trips. GM's later 2017 table 17OBDG04 moved this kind of switch-versus-switch plausibility to P257D, which matches the J2012 range/performance wording. A broken switch or wiring can disable auto-start and raise a warning.
What you may notice: Check engine light after two trips (GM Type B)
Auto-stop or hybrid engine start disabled
Hood-open warning while the hood is closed
Likely causes: LikelyHood switch dirty, corroded or misadjusted
PossibleDamaged wiring or connector at the hood latch
RareBent hood latch after a front-end repair
Inspection (ITP): Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
Repair: Easy · Often possible to do yourself.Typical cost: €20 – €250
Related codes: P257D

Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.