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.
Ford Ranger · 1995–1997
On mid-1990s Rangers, a sticking idle air control valve is a documented cause of hard starting, rough or unstable idle, and stalling. The IAC meters bypass air for cold-start and idle; carbon buildup gums up the pintle so it can't regulate idle airflow, especially noticeable on cold starts or when coming to a stop.
Common Symptoms
- Hard starting, especially when cold
- Rough, hunting, or high/low idle
- Stalling at idle or when coming to a stop
How to Fix
Remove and clean the IAC valve and throttle body with throttle-body/carb cleaner; if cleaning does not restore stable idle, replace the IAC valve. This is an inexpensive DIY-level repair. Cleaning the throttle bore at the same time helps prevent recurrence.
Sources for this issue (1)
Volvo S70 · 1998–2000
The Volvo S70 turbo and non-turbo 5-cylinder engines develop PCV (Positive Crankcase Ventilation) system blockage. The breather box/flame trap clogs, causing excessive crankcase pressure that pushes oil past gaskets and seals.
Common Symptoms
- Oil leaks from valve cover
- Oil consumption increase
- Oil residue around turbo
- Whistling noise from engine
- Rough idle
How to Fix
Diagnose the PCV system by checking for excessive crankcase pressure at the oil filler cap or dipstick tube, then inspect the breather box/oil trap, flame trap fittings, and all related vacuum hoses under the intake manifold for sludge blockage or collapse. The proper repair is a full PCV service kit installation—typically replacing the oil trap, banjo fittings, hoses, intake manifold gasket, and cleaning the ports in the block and manifold; on turbo models, also inspect and clean the turbo oil return area and replace any leaking cam, valve cover, or rear main seals only after crankcase ventilation is restored. If oil leaks have been present for a while, recheck for residual seepage after the PCV repair before replacing seals unnecessarily. Typical cost is about $250-$450 in parts and 4-7 labor hours, for a total of roughly $700-$1,400 depending on engine configuration and how many oil leaks need follow-up repair.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- IPD 124712 early P80 turbo PCV breather system kit
complete oil-trap and breather-hose service for the 1998 turbo branch Fitment/availability: 1998 Volvo S70 GLT/T5 turbo P80 with ME4.4; includes alternate inlet elbow for the early or revised turbo inlet tube Fitment/availability: In sto…
- Genuine Volvo 114832 1998 non-turbo PCV breather system kit
complete PCV service for the distinct 1998 non-turbo routing Fitment/availability: 1998 Volvo S70 non-turbo B5254FS P80 with ME4.4, automatic or manual Fitment/availability: In stock with Add to Cart live when reviewed
- Genuine Volvo V70T100 late P80 turbo PCV breather system kit
complete PCV service for the 1999-2000 turbo configuration Fitment/availability: 1999-2000 Volvo S70 turbo P80 branch; validate the exact VIN, engine and installed routing before ordering Fitment/availability: In stock with Add to Cart a…
- Genuine Volvo KIT-516300 late P80 non-turbo PCV breather system kit
complete PCV service for the 1999-2000 non-turbo configuration Fitment/availability: 1999-2000 Volvo S70 non-turbo P80 branch; validate VIN and installed hose routing before ordering Fitment/availability: In stock with Add to Cart and Bu…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Mazda 626 · 1993–1999
Ford E-Series · 1997–2004
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.