P2509ECM/PCM Power Input Signal Intermittent
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2509 records a brief loss of the engine module's supply, a dropout rather than a lasting low or high value. Two Cummins-powered pickups show how easily it appears. Nissan warns for the 2016 Titan XD with the 5.0 L diesel: wait at least two minutes after switching off before disconnecting either 12 V battery, otherwise P2509 and P181B are stored; such codes may be erased but are not a warranty repair. FCA lists P2509 among faults addressed by a PCM reflash for 2018 Ram 2500/3500 with the 6.7 L Cummins, where customers saw the MIL. The module's after-run, interrupted by a cut supply, is what the check catches. Persistent values belong to P2507 and P2508, plausibility to P2506. Real loose battery clamps or relay contacts give the same code.
- What you may notice
- MIL on, often without drivability complaint
- Code appears right after battery work
- Likely causes
- LikelyBattery disconnected before the module finished its after-run
- PossibleLoose battery clamp, ground or supply connector
- PossibleModule software too sensitive, fixed by reflash (Ram 6.7 L)
- RareIntermittent main relay contact
- 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: €0 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.