VW Fox Diesel Starting Issues, Ignition Switch Mystery

Had the exact same starting issue with my 2013 VW Polo diesel last winter. With some experience working on cars, I initially thought it was the starter motor, but it turned out to be much simpler. The dashboard lights would come on, but the starting was completely inconsistent, sometimes fine, sometimes nothing. After a few failed attempts to diagnose it myself, I took it to a workshop. They found a blown fuse connected to the ignition circuit. The car electronics were getting irregular power, causing those unusual starting problems and rough running. Total repair cost was 52€ including diagnostics and the new fuse. Quick fix that solved all the issues, no more unusual shutoffs or starting problems since then. What engine size does your Fox have? Also, are you getting any warning lights on the dashboard when these issues occur? This information would help determine if youre dealing with the same problem. Worth checking your fuse box first, its a simple fix that could save you time and money before exploring more complex issues like the ignition switch or starter motor.

Thanks for sharing your experience. My Fox had its last service at 25603km, so these issues are quite unexpected. When my car electronics misbehave, no warning lights appear on the dashboard before or during the failed starts. The ignition key turns normally, but the engine response is completely unusual. I just checked the fuse box following your advice, all fuses look intact, but I noticed some corrosion on the battery terminals which might be relevant. Would battery terminal cleaning be worth trying before going to a workshop, or should I skip straight to professional diagnostics given the unusual engine shutoffs while driving?

Thanks for the extra details. Unlike my Polo where a blown fuse was the culprit, corroded battery terminals could definitely cause your symptoms. In fact, after fixing my fuse issue, I later experienced similar problems from dirty battery connections. Poor battery contact can cause the exact behavior youre describing, unusual starting issues and the engine cutting out while driving. When the ignition switch signals for power, corroded terminals can prevent reliable current flow to the starter motor and other car electronics. Before spending money at a workshop, I recommend: 1. Clean the battery terminals with a wire brush 2. Check the terminal clamps are tight 3. Apply some battery terminal grease to prevent future corrosion If the problems continue after cleaning the connections, then professional diagnostics would be the next step. The intermittent engine shutoffs while driving could point to a failing ignition switch or other electrical issues that need proper testing. The repair costs can vary significantly, from just 20€ for basic electrical cleaning to 200€+ if the ignition switch needs replacement. But start with the simple fix first. Would you like guidance on the proper way to clean battery terminals? Its a straightforward DIY job that could save you a workshop visit.

Thanks for the detailed reply. I will definitely try cleaning the battery terminals first since its a simple fix I can do myself. Looking at the battery now, theres quite a bit of white crusty buildup that could be causing the poor connection. Given the unusual engine shutoffs and starting issues, I want to be thorough with the cleaning. Could you share the specific steps for properly cleaning battery terminals? I have a wire brush but want to make sure I do it correctly and safely. Also, is regular petroleum jelly okay to use as terminal grease or should I get a specific product? If cleaning the terminals doesnt resolve the car ignition problems, I will take it to a workshop for professional diagnostics. The unusual shutoffs while driving are concerning enough that I dont want to risk getting stranded somewhere. Better to properly diagnose any potential starter motor or deeper electrical problems.