P0505: Idle Control System
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Usually driveable; stalling at stops is the risk that sets urgency.
Symptoms
- Idle too high, too low, or hunting
- Stalling when coming to a stop
- Stalling when AC engages
Likely causes, most common first
- Carbon-fouled throttle body or idle passages
- Idle air control valve failing (cable-throttle designs)
- Vacuum leak confusing idle control
Read P0505 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
P0505 means the idle control system cannot hold the target rpm. On older cable throttles a dedicated idle valve does this job; on modern drive-by-wire the throttle plate itself does, and carbon around the plate is the usual saboteur.
Cleaning fixes the majority. If idle problems persist after cleaning and relearn, look for vacuum leaks - unmetered air is idle control's natural enemy.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0505
“- started shutting shutting off at while in drive. - started having reduced power - started idiling high while driving - initially there was no codes - last night I drove, I put in drive gear but it was delayed so I had to keep moving from park to drive for it to full go into drive - the codes came P0325 P0505 P0507 P0700 P1101 P2714 After I was driving up an incline the car stopped moving forward and started reversing backwards. One other independent shop advised they were able to produce but couldn't figure out the problem because no code were shown at the time. There has been many people having the same issues I started off with and I found the forum to file a report .”2019 Chevrolet Malibu · Nov 2025
“Check engine light came on and the performance of the vehicle is bad. Bad idle, weak engine, just the car is not performing properly. I used the scanner to see the code and I had more than one . P0171 p0505 p117b p0441 p0455 . Fuel/air mixture is lean . And I hear the fuel pump making that noise that indicates a bad fuel pump. It's when I put the key in I hear it loud enough and if I turn the key on it does it again. When I put it on p it revs and rpm goes up and then comes down, up again down again ... When stopped at a red light the car wants to move and rpm keeps shaking. *tr”2018 Toyota Camry · Jun 2020
“Awareness needs to be made on the 2000 nissan maxima, the car will have a ecu breakdown resulting in the car to shut off at any given time. A trouble code of p0505 will trigger off in the car resulting in an insane repair cost. Numerous cars are affected and nissan refuses to perform a recall on this car. Its a matter of time before one of these nissans shuts down at the wrong time resulting in someone's death. There are pages upon pages of posts with this problem. *tr”2000 Nissan Maxima · May 2008 · 100,000 mi
Show 2 more owner reports
“Tl*the contact owns a 1998 honda accord. The contact stated that the engine light was illuminated, but eventually dimmed. The service dealer stated that they would charge her just to inspect the vehicle. The dealer advised her to return when the failure recurred. The engine light illuminated again one year later. The contact returned to the service dealer who stated that the vehicle was only guaranteed for 80,000 miles. The codes issued by the maintenance technician regarding the failure were p0420, p0505, and p1456. The purchase date and powertrain were unknown. The current mileage is 97,596 and failure mileage was 80,000.”1998 Honda Accord · Jun 2006 · 80,000 mi
“It was determined that all 4 oxygen sensors needed to be replaced. The consumer found that there was an extended warranty, but was told that the problem wasn't bad enough for a total recall. *sc recall campaign: recall number: 99v347003. The towing packet light kit had blown out and was replaced. The consumer stated that the engine light has been on since purchase of the vehicle. Vehicle stalled while being driven by the consumer. When started again the check engine light appeared. After having the vehicle checked again it registered a code of p0505/possible idle control system. *tc”2000 Toyota Tundra · Aug 2004
Cars that report P0505 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0505?
Usually driveable; stalling at stops is the risk that sets urgency.
How much does it cost to fix P0505?
Typical US repair costs range from $80 for the simplest fix (throttle body / iac cleaning) 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.