P0508: Idle Air Control System Circuit Low
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Usually - idle faults rarely strand, but stalls in traffic are possible.
Symptoms
- Stalling or very low idle
- Erratic idle after battery disconnect
Likely causes, most common first
- Idle control circuit shorted low
- IAC valve failed
- Wiring damage
Read P0508 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0508 reports the idle air control circuit stuck electrically low - mostly a cable-throttle-era code, since drive-by-wire cars idle with the throttle plate itself. The valve motor or its wiring has failed.
Cleaning sometimes revives a sticking valve; a truly shorted one needs replacement. Straightforward work on most engines of that generation.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Cars that report P0508 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0508?
Usually - idle faults rarely strand, but stalls in traffic are possible.
How much does it cost to fix P0508?
Typical US repair costs range from $80 for the simplest fix (iac valve) to $500 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0508. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.