VW Crafter Intake Issues: Hissing + Poor MPG

I had a very similar issue with my 2010 VW Transporter TDI. Initially noticed the same symptoms, poor fuel economy, hissing noise, and check engine light. After some basic troubleshooting, my workshop found a cracked vacuum hose near the throttle body that was causing an air leak. The engine misfire symptoms got worse under load because more air was being pulled through the damaged hose. The repair was straightforward, they replaced the faulty intake hose and performed a quick diagnostic check to ensure there were no other vacuum leaks. Total cost was 100€ including parts and labor. The symptoms completely cleared up after the fix. Fuel economy returned to normal and the check engine light went off. To help diagnose your specific case, could you share: Current mileage on your Crafter, Any other unusual engine sounds or performance issues, Whether the issue started suddenly or developed gradually, If any recent work was done on the intake system These details would help determine if your issue is similar to what I experienced.

Thanks for the feedback regarding vacuum hose issues. After having my Crafter serviced last month, I started noticing these symptoms. During leak detection tests, the mechanic found multiple small cracks in the intake manifold gasket, causing the vacuum leak. They suggested replacing both the gasket and inspecting the throttle body while its apart. The engine misfire is definitely more noticeable when cold. Would appreciate any suggestions on whether I should replace additional components while they have the intake system opened up. Wondering if replacing vacuum lines as preventive maintenance makes sense at 182357KM.

Your experience matches what I went through with my VW Transporter. When my mechanic replaced that cracked vacuum hose, they found the intake manifold gasket was also deteriorating. Given the similar age of our vehicles, I opted to do a complete intake system service. The preventive maintenance was worth it. Along with the vacuum lines and gasket, I had them check the air filter and clean the throttle body. The turbocharger seals were also inspected since they can affect fuel economy and cause similar symptoms when failing. The total job came to around 450€, but it resolved all the issues and prevented future problems. The fuel economy improved beyond just fixing the initial leak, and the engine runs noticeably smoother, especially during cold starts. At your mileage, replacing those vacuum lines is smart preventive maintenance. Age causes rubber components to become brittle, so addressing them all at once saves labor costs versus multiple repairs. The improved engine performance and fuel economy made the investment worthwhile in my case. Just ensure they do a thorough vacuum leak test after everything is reassembled to confirm all connections are properly sealed.

Thanks for all the information regarding the intake system service. Makes sense about the vacuum lines becoming brittle over time. After discussing with my mechanic, I decided to go ahead with the complete intake system overhaul while they have it apart. Going to have them replace all vacuum lines, clean the throttle body, and inspect the turbocharger seals since the system will already be opened up. Better to address everything now rather than having to take it back in a few months for another repair. The quoted price of 475€ seems fair considering the scope of work. Really hoping this comprehensive service will resolve the cold start issues and restore my fuel economy. Will update once the repairs are complete to confirm if this fixed all the symptoms. Just hoping to avoid any future intake manifold problems since the engine has quite a few miles on it now.