P0505: How to Diagnose & Fix — Idle Air Control System Malfunction
9 vehicles · 7 makes · $20-$700 repair
How to diagnose and fix P0505: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Nissan Cube · 2009–2014
Multiple owners report the Cube stalling unexpectedly while driving at various speeds, including highway speeds. The engine shuts off without warning, causing loss of power steering and power brakes. In some cases, pumping the accelerator at the moment of stalling can catch the engine before it dies completely. The issue has been linked to faulty crankshaft position sensors, throttle body failures, and ECM software bugs.
Common Symptoms
- Engine stalls without warning while driving
- Loss of power steering and brakes during stall
- Engine dies at idle or low speed
- Check engine light may or may not illuminate
- Difficulty restarting after stalling
How to Fix
Start with cleaning the throttle body and checking for vacuum leaks. Replace the crankshaft position sensor if codes P0335 or P0340 are present. Have the ECM software updated at a Nissan dealer. If the problem persists, the throttle body assembly may need replacement. Always keep up with spark plug replacement at the recommended 105,000-mile interval.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Nissan crankshaft position sensor 23731-1VA0A
2009-2014 Cube 1.8L on the live fitment table; confirm VIN and connector/current supersession.
- Genuine Nissan camshaft position sensor 23731-EN22A
2009-2014 Cube 1.8L on the live fitment table; confirm VIN/current supersession.
- Genuine Nissan electronic throttle body 16119-9SE0A
Confirm VIN/core terms and complete all required electronic-throttle learning.
- Genuine Nissan spark plug 22401-JD01B
Quantity four; verify VIN, plug specification and gap-handling instructions.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipClean the throttle body with CRC Throttle Body Cleaner every 30,000 miles — this prevents carbon buildup that causes stalling.
- WarningStalling at highway speeds is extremely dangerous. If it happens more than once, do not drive until diagnosed.
Honda Civic · 1996–2005
The idle air control valve (IACV) on the throttle body meters the air that bypasses the closed throttle at idle. On D-series Civics it fouls with carbon and the pintle sticks, so the ECU can no longer stabilize idle. Symptoms are a hunting/surging idle, abnormally high idle, or the engine dying when coming to a stop or cold. It is a common, inexpensive fix that owners search because the car stalls at intersections and feels erratic.
Common Symptoms
- Idle hunts up and down at stops
- Stalls when decelerating to a stop or when cold
- Abnormally high idle speed
- Rough shaking idle
- Stalls with A/C or electrical load applied
How to Fix
Remove and clean the IACV and throttle body with carburetor/throttle-body cleaner; replace the IACV if the pintle is stuck or the coil is out of spec. Reset idle relearn afterward. Clean the associated throttle-body ports (fast-idle thermovalve on older D-series).
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- 1996 Honda Civic genuine idle-control-valve catalogOEMHonda 16022-P2E-A51 / 36450-P2J-J01 / 16022-P2A-J01 by confi
Select exact VIN and do not transfer
- 2001-2005 Honda Civic genuine idle-control-valve catalogOEMHonda 16022-PLC-J01 automatic/CVT / 16022-PLC-003 5MT
Enter VIN because GX, Si and other engine/emissions branche
- Genuine Honda 16176-P2A-004 throttle-body gasketOEMHonda 16176-P2A-004
Do not buy for a cleaning procedure that does not detach the throt
- Genuine Honda 16176-PMR-A01 throttle-body gasketOEMHonda 16176-PMR-A01
Enter VIN because alternate engine/emissions branches exist; do not buy unless the procedure removes the
- CRC 05078 throttle body and air-intake cleaner, 12 ozOEMCRC 05078 / AutoZone SKU 55922
Do not spray or soak the IACV electrical coil/motor, MAF sensor or incompatible c
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (2)
Toyota 4Runner · 1996–2002
The 3.4L 5VZ-FE uses a rotary-solenoid Idle Air Control (IAC) valve on the throttle body to manage idle. Over high mileage the IAC passages and valve clog with carbon and oil deposits, producing erratic idle (hunting between ~700 and ~1200 RPM), high idle, or low idle that shakes and stalls — often stalling at stops or when the A/C compressor loads the engine. It's a very frequent, well-documented maintenance item for 5VZ-FE 4Runners/Tacomas and commonly sets P0505 (idle control system malfunction).
Common Symptoms
- Erratic/hunting idle (surging up and down)
- High idle when warm or low idle that shakes
- Stalling at stops or when A/C engages
- Check engine light P0505 (or P0506/P0507)
- Rough idle after cold start
How to Fix
Remove and clean the IAC valve and throttle body bore/passages with throttle-body cleaner; inspect the connector and harness for corrosion or broken pins. Cleaning frequently restores normal idle, but a worn valve may need replacement — use an OEM/Denso IAC valve, as non-OEM units are a frequent cause of repeat P0505. Also rule out vacuum leaks, which mimic the same code. Cleaning is nearly free; an OEM IAC valve runs roughly $100-300, DIY-friendly.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Toyota 22270-62050 idle air control valve
conditional valve replacement after leak, circuit and cleaning tests fail Fitment/availability: retailer explicitly lists 1996-2001 Toyota 4Runner V6 3.4L 5VZ-FE; not approved here for 2002 without VIN confirmation Fitment/availability: …
- Genuine Toyota 22215-62180 IAC valve gasket
new seal when the applicable IAC valve is removed for cleaning or replacement Fitment/availability: retailer explicitly lists 1996-2000 Toyota 4Runner 3.4L 5VZ-FE; confirm VIN for 2001 and do not apply to 2002 without catalog confirmatio…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (2)
Ford Ranger · 1995–1997
Volvo XC60 · 2010–2015
Find P0505 by make
Browse every documented model and issue for your make.
P0505 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0505 mean?
P0505 stands for "Idle Air Control System Malfunction." P0505 indicates a malfunction in the idle air control (IAC) system, which manages how much air bypasses the throttle plate to keep the engine idling smoothly at the correct RPM. On older systems this is a dedicated IAC valve/motor; the computer uses it to raise idle for cold starts, A/C load, or accessory load. When the system can't maintain the target idle, you may get a high or low idle, surging, rough idle, or stalling — especially at stops or when cold. The cause is usually a dirty or failed IAC valve, but vacuum leaks and electrical faults are common too.
What are the most common causes of P0505?
The most common causes of P0505 are: Dirty or carbon-clogged idle air control valve, Failed IAC valve motor or stuck pintle, Vacuum leak in the intake system, Dirty throttle body or sticking throttle plate, Wiring or connector fault in the IAC circuit, Faulty PCV system causing unmetered air, PCM/ECM control fault. The specific cause varies by vehicle.
How much does it cost to fix P0505?
Repair costs for P0505 range from $20 to $700, depending on the vehicle and root cause.
Which vehicles are affected by P0505?
Au7o has documented P0505 across 9 vehicle models from 7 manufacturers: Ford, Honda, Mazda, Nissan, Toyota, Volkswagen, Volvo.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.