P2531
Ignition Switch Run Position Circuit Low
The ignition switch Run-position input reads stuck low — short to ground or a permanently closed contact. The ECM cannot tell when the operator releases the switch from Run, so accessory and crank logic gets confused.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Run input wire shorted to groundCommon
- Switch contact stuck closedPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Ignition Switch
- Wiring Harness
P2531 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.