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.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.