OBD-II code · Powertrain (generic, extended)
P256B Engine Idle Speed Selector Sensor/Switch Range/Performance
The idle-speed selector input is electrically intact but the value does not match a valid preset — multiple positions or a non-mappable value. Often a sticky multi-position switch.
Is it safe to drive with P256B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyContaminated rotary contact
- Less likelySensor element aged beyond calibration window
- Less likelySensor mounting loose - signal damping
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
- P2568Turbocharger Boost Control Position Sensor Circuit High
- P2569Direct Ozone Reduction Catalyst Temperature Sensor Circuit Low
- P256CEngine Idle Speed Selector Sensor/Switch Circuit Low
- P256DEngine Idle Speed Selector Sensor/Switch Circuit High
- P256EEngine Idle Speed Selector Sensor/Switch Circuit Intermittent/Erratic
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.