VW Fox Diesel Stalling: Idle Speed Troubleshooting

Had the same symptoms on a 2005 VW Polo 1.9 TDI. The engine would stall at idle speed, particularly after cold starts. The issue was indeed linked to the idle control system, but the root cause was heavy carbon buildup in the intake manifold and throttle body. The throttle body needed thorough cleaning and the idle air valve required replacement since carbon deposits had damaged its internal components. These components regulate the air supply during idle, and when contaminated, they cant maintain stable idle speed. The stalling engine symptoms got worse over time, especially during the first few minutes after starting. This was definitely a serious issue that needed immediate attention since it could lead to complete engine failure if left untreated. The repair involved: Complete intake manifold removal and cleaning, Throttle body cleaning and recalibration, Air valve replacement, New intake gaskets, Diagnostic system reset After the repair, the idle speed stabilized and the check engine light cleared. The engine ran much smoother overall. Would strongly recommend getting this checked soon, as continued stalling can damage other engine components.

Thanks for sharing your experience with the intake system cleaning. My Fox had exactly the same idle speed problems. I was wondering, do you remember what the total repair cost was? My mechanic quoted me 450€ just for parts, which seems high. Also, has your car been running smoothly since the repair? I have heard these idle issues can sometimes come back if the IAC valve gets dirty again, so I am a bit worried about that. My engine idle is still not perfect after the initial cleaning.

The total repair came to 425€ at my shop, which was actually less than your quote. The service fixed the bad idle air control valve completely and included a thorough cleaning of the heavily contaminated intake system. My engine idle has been rock solid for the past 8 months since the repair. The throttle body and air valve are working perfectly now with no stalling engine issues whatsoever. The key was getting all the carbon deposits removed professionally rather than just doing a basic clean. The technician mentioned that to prevent future idle control problems, its important to: Use high quality fuel, Change the air filter regularly, Get the intake cleaned every 60000km A proper repair should last several years if you follow these maintenance steps. The initial cost might seem high, but its worth it to prevent more expensive engine damage from continued stalling. The smooth idle my car has now makes me wish I had fixed it sooner.

After struggling with the idle speed problems in my Fox, I finally took it to a different mechanic who seemed more knowledgeable about VW diesels. The car had the same intake system issues you mentioned. They did a complete cleaning of the intake manifold and replaced the IAC valve. The total bill came to 380€, which was much better than the 450€ quote I got earlier. The mechanic showed me all the carbon buildup they cleaned out, it was shocking how dirty the system was. The idle control is working perfectly now and the engine runs so much smoother. They also gave me some tips about preventing future problems with the air valve and idle speed. I am making sure to use better quality fuel and will get the intake cleaned at the recommended intervals. Really glad I got this fixed properly instead of trying cheap temporary solutions. No more stalling at traffic lights!