VW Sharan Stalling: EVAP System Leak Signs

Had nearly identical issues with my 2005 VW Touran last summer. As someone with moderate experience working on VWs, I initially thought it was just the gas cap too, but the issue turned out to be more complex. After proper leak detection tests, the workshop discovered a defective activated charcoal filter in the emission control system. The symptoms matched yours exactly, rough idle, stalling, and inconsistent fuel tank pressure readings. The charcoal filter is part of the evaporative emission control system and when it fails, it can cause exactly these air flow and pressure problems. The repair cost me 275€ including parts and labor. The fix resolved all the symptoms and the check engine light hasn't returned since. The whole process took about 3 hours at the shop. Could you share more details about your Sharan? Specifically: Engine size, Current mileage, How long has the check engine light been on, Have you noticed any fuel smell, Does the problem get worse after refueling This information would help confirm if your system failure is similar to what I experienced, as these emission control issues can have various causes.

Last complete service was done at 135000km and now showing these problems at 140267km. During diagnostics, the purge valve showed erratic behavior on the scanner, which makes me suspect its more than just the charcoal filter. When the engine stalls at idle, there is a noticeable fuel efficiency drop as the system tries to compensate. Based on what you described with your Touran, I will have the workshop run a complete pressure test on the evap system. Thanks for sharing the repair cost details, helps set expectations for the potential fix.

Thanks for those additional details. The mileage gap from your last service matches when these issues typically start appearing in VW evap systems. After dealing with my Touran's problems, I learned these symptoms often point to multiple failing components working together. You are right about the purge valve, the erratic readings you mention are a classic sign. In my case, while the charcoal filter was the primary culprit, the mechanic also found that the purge valve had degraded from the system running inefficiently. The air flow problems caused by the faulty valve were making the fuel tank pressure sensor readings jump around. For comprehensive testing, make sure they check: Complete EVAP system pressure integrity, Purge valve operation under different RPM conditions, Fuel tank pressure sensor calibration, All related vacuum lines for micro-cracks The repair cost might be higher than what I paid since you likely need both the purge valve and filter replaced. Based on current parts prices, expect around 400-450€ for both components plus labor. The fuel efficiency drop you noticed is typical when the EVAP system isnt working properly, the engine management system runs rich trying to maintain idle.

Thanks for the detailed breakdown. After running more tests, the scanner shows both purge valve malfunction codes and vacuum system errors, confirming your suspicion about multiple issues. Booked the car in next week for the full system inspection and likely replacement of both components. The fuel efficiency has dropped from 7.2L/100km to around 8.5L/100km during city driving, so fixing this should help reduce fuel costs too. Really hoping the pressure sensor itself is still good since that would push costs even higher. Will update once the repair is done, but your experience has helped set realistic expectations for both the diagnosis and repair costs. The emission control system is clearly more complex than I initially thought with my gas cap theory.