VW Sharan Idle Troubles Point to Faulty Air Intake

A faulty air intake system caused similar idle problems on my 2012 VW Touran diesel. The check engine light appeared intermittently at first, then became constant. The main issue turned out to be a vacuum leak where the pump connects to the intake valve. Key symptoms matched yours: Rough idle, especially when cold, Inconsistent engine performance, Check engine light staying on, Air intake system making subtle whistle sounds The vacuum hoses needed complete inspection as several had deteriorated. This is a common failure point on VW diesels from that era. The mechanics found cracks in multiple vacuum hoses and a loose connection at the brake booster. This repair requires proper diagnostic equipment to pinpoint all vacuum leaks. A smoke test revealed the full extent of the problem. While not immediately dangerous, ignoring these symptoms can lead to increased fuel consumption and potential damage to other engine components. When choosing a mechanic, ensure they: Have proper VW diagnostic tools, Can perform vacuum system smoke tests, Will thoroughly check all hose connections, Inspect the entire air intake system

Thanks for sharing those details about the vacuum leak problem. Your symptoms do sound very similar to what I experienced with my Sharan. My check engine light also kept coming on, and the engine stalling was getting worse, especially during cold starts. The manifold pressure readings were all over the place. Did you remember roughly what the total repair cost was? My mechanic is quoting a pretty high price and I want to compare. Also, have you had any throttle body issues since the repair was done? Mine sometimes feels a bit rough when accelerating, so I'm wondering if that might be related.

After dealing with those air intake and vacuum hose issues on my Touran, I had them fixed properly two weeks ago. The manifold pressure is now stable and the check engine light hasnt returned. Total cost was 175€ for replacing the defective hose connection between the pump and valve. Much more reasonable than some quotes I received earlier. The rough acceleration you mentioned could definitely be connected to your vacuum system problems. Once the proper air flow is restored, throttle response should improve significantly. My engine now runs smoothly without any idle problems that plagued it before. After fixing the air intake system, the improvement was immediate. No more stalling during cold starts and the engine maintains steady idle. Make sure your mechanic thoroughly checks all vacuum hoses while doing the repair, as multiple leaks can often develop around the same time in these systems. If your manifold pressure readings are inconsistent, its definitely worth getting those hose connections checked. A proper diagnosis and repair now can prevent more extensive problems later.

I finally got my Sharan fixed last week after getting a second opinion from another mechanic. The engine stalling issues were exactly what you described, multiple vacuum leaks causing irregular air supply to the engine. The new shop did a complete smoke test and found three separate leaks, including a major one near the throttle body. The total repair came to 230€, which included replacing all the damaged vacuum hoses and testing the entire air intake system. Much better than the 600€ quote from the first mechanic who didnt even mention checking for vacuum leaks. The idle problems cleared up immediately after the repair. No more check engine light and the throttle response is smooth again. The mechanic also cleaned the air intake valve while doing the work, which helped eliminate that rough acceleration I was experiencing. Really glad I asked here first, saved me from overpaying for an incomplete diagnosis. The car runs like new now and maintains a steady idle even during cold starts.