P0506 Idle control system RPM lower than expected
- System
- Powertrain - engine and transmission
What P0506 means
The name "Idle control system RPM lower than expected" spells out the comparison: with the pedal released, the computer measured engine speed and held it against the idle speed it was asking for, and the measured figure came in below it. RPM is the engine's revolutions per minute, and "than expected" means the car's own commanded idle for the conditions of that moment, not one fixed number. Its twin P0507 is the same comparison landing on the other side.
This is a standard code. It means the same thing on every make of vehicle.
What the program shows for P0506
The Engine speed card's warm-idle band is what the program draws on the low side of this reading: the card goes amber under 600 rpm and red under 480. That band is applied only while the engine is idling — it is dropped above 1,100 rpm so revving raises no false alarm, and under 300 rpm the program reads the engine as stopped.
The Dashboard shows Vehicle speed, Engine speed with its warm-idle band, Relative throttle, Throttle actuator and System voltage, plus Oil temp (the program has no oil pressure reading). The Trip screen keeps Distance, Average speed, Time moving and Time idling, and the Analysis screen's At idle table gives the idle rpm for a recording. Compare shows idle rpm and throttle Before and After between two recordings.
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