OBD-II code · Powertrain (generic, extended)
P256D Engine Idle Speed Selector Sensor/Switch Circuit High
Idle-speed selector input reads stuck high — short to battery voltage or analog signal at maximum. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P256D?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySwitch wire shorted to battery voltage
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
Symptoms
- Check engine light on
- Idle speed too high, too low, or unstable
- Possible stalling at idle or after cold start
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Idle Speed Selector Switch
Related codes
- P256AEngine Idle Speed Selector Sensor/Switch Circuit/Open
- P256BEngine Idle Speed Selector Sensor/Switch Range/Performance
- P256CEngine Idle Speed Selector Sensor/Switch Circuit Low
- P256EEngine Idle Speed Selector Sensor/Switch Circuit Intermittent/Erratic
- P256FA/C Request B Circuit Range/Performance
- P2570Direct Ozone Reduction Catalyst Temperature Sensor Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.