What P0506 means
CARB requires the idle speed control to be monitored: gasoline engines must flag a fault if the target idle speed is not reached within +200/−100 rpm, diesels within ±30 %.
How the engine computer detects it
Older engines use a separate idle air control valve that bypasses the closed throttle; with electronic throttle the throttle itself controls idle and no separate valve exists. P0506 means the idle speed of the warm engine at standstill stays too low despite fully used control. GM uses more than 91 rpm filtered for 10 s (MIL after two trips), Ford gasoline −100 rpm plus a correction above 1 lb/min, Ford diesel −100 rpm for 5 s, Subaru −100 rpm with the correction at its limit for 10 s three times. Typical are deposits, extra load or a restricted intake or exhaust.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Idle too low, engine shakes
- Engine stalls when stopping or with A/C on
- Check engine light after two trips
Common causes
- Deposits at the throttle or bypass channel, or gummed idle valve Most likely
- Extra load: stiff accessory drive, transmission or converter Possible
- Intake or exhaust restricted (air filter, catalyst) Possible
- Idle valve or throttle actuator faulty, wrong learned value Possible
- Mechanical engine damage (low compression) Less likely
How to diagnose P0506
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: idle control, throttle body, idle air control valve, engine control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P0506 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Kia Sorento | 2014–2021 | 3 | — |
Counts of owner complaints to the NHTSA that mention P0506 (17 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 5
- Vehicle speed, idle control and auxiliary inputs
- 06
- Specific fault
Questions drivers ask
Can I drive with code P0506?
Usually yes for a short time, if the car drives normally, the temperature gauge reads normal and the check engine light is steady. If the light flashes, the engine loses power or overheats, or other warning lights come on, pull over and have it checked.
Will my car pass an emissions inspection with P0506?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0506 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P0506 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0506. They can point to a shared cause, so it's worth checking them together.
- P0300Random/Multiple Cylinder Misfire Detected6 complaints
- P0301Cylinder 1 Misfire Detected5 complaints
- P0303Cylinder 3 Misfire Detected5 complaints
- P0302Cylinder 2 Misfire Detected4 complaints
- P0304Cylinder 4 Misfire Detected4 complaints
- P0106Manifold Absolute Pressure/Barometric Pressure Sensor Circuit Range/Performance3 complaints
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.