Audi Q3 Diesel Cold Start: Glow Plug Warning Signs

Had almost the same issue with my 2013 Audi Q5 diesel. Have some hands-on experience with basic diesel maintenance but leave the complex stuff to professionals. The symptoms were identical, cold start problems and the check engine light came on. The preheating lamp staying lit was the big clue. Took it to an independent workshop where they ran diagnostics and confirmed a faulty glow plug on cylinder 2. The repair involved replacing the defective glow plug and checking the others. Total cost was 440 Euro including parts and labor. Since the fix, cold starts have been smooth and the engine light cleared up completely. Before you proceed, could you share: Any engine misfire symptoms? Does the engine struggle more in cold weather? Have you noticed black smoke during startup? Which engine variant does your Q3 have? This info would help determine if your case is similar and might save diagnostic time at the workshop. A proper diagnosis is crucial since glow plug issues can sometimes indicate other underlying problems with the fuel system.

Thanks for sharing your experience. My Q3 is running at 9456 KM and had its last service 3 months ago. The engine misfire symptoms are most noticeable during cold starts, especially after the car sits overnight. No black smoke, but the engine combustion seems rough for the first minute. The problem gets worse in colder conditions. For reference, I have the 2.0 TDI variant. The check engine light started appearing intermittently at first, but now stays on constantly along with the preheat indicator. Interesting that your repair costs were 440 Euro, helpful to know what I might expect. Based on these matching symptoms, I will schedule a diagnostic check focusing on the glow plug system. Will update once I have more information.

Thanks for providing those additional details. Since my Q5 repair, I have learned that consistent preheating lamp issues combined with rough engine combustion during cold starts are classic indicators of glow plug problems. Your 2.0 TDI symptoms match mine exactly, the intermittent check engine light that eventually stayed on was particularly familiar. The absence of black smoke in your case is actually good news, as this often indicates the fuel efficiency and injection system are likely working properly. Since your car has relatively low mileage and recent service, I would definitely focus on the glow plug system first. My mechanic mentioned that sometimes one faulty plug can trigger the persistent preheating lamp, even if the others are fine. When they diagnosed my Q5, they found the glow plug resistance values were out of spec, which explained the cold start issues. The repair solved both the starting problems and the warning lights. Quick tip: While waiting for the repair, try to avoid multiple short trips in cold weather, as this can put additional stress on the remaining functioning glow plugs.

Thanks for the detailed response and tips about cold starts with diesel engines. The information about glow plug resistance values is particularly helpful, that could explain my starting issues. Speaking of cold weather operation, I just remembered another symptom: the engine takes noticeably longer to turn over when starting in the morning compared to a few months ago. Given all the feedback about similar experiences with faulty glow plugs, I am now quite confident this is the root cause of my fuel efficiency issues during cold starts. I will schedule the diagnostic check tomorrow and request they specifically test the glow plug system. The 440 Euro repair cost reference gives me a good baseline for what to expect. Will avoid those short trips until it is fixed to prevent any additional strain on the engine combustion system. Before the repair, I will collect some videos of the cold start behavior to show the mechanic. Hoping this helps speed up the diagnostic process and leads to a straightforward fix like in your case.