P256CEngine Idle Speed Selector Sensor/Switch Circuit Low
- Generic OBD-II code · Powertrain
- How the car detects it
- P256C says the idle speed selector input is pulled below its lowest valid level, typically by a signal wire shorted to ground or a switch with an internal short. Where the selector is a simple ground-switched input, the controller would read such a short as a permanent request, so a dedicated low code presupposes a coded or monitored circuit. No manufacturer documents P256C publicly. A raised idle that appears without driver input is not automatically this fault: Ram's 2025 6.7L Cummins bulletin S2509000007 lists automatic modes such as cab warm-up at 1000 rpm below 4.4 °C ambient or inverter support between 700 and 1500 rpm. P256D is the high-side code. Expect the raised idle to be unavailable or the code to return after every key cycle.
- What you may notice
- Raised idle unavailable
- Code returns after every key cycle
- Likely causes
- LikelyIdle selector wire shorted to ground
- PossibleInternal short in the idle selector
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.