Audi A2 Diesel Glow Plug System Failure Symptoms

Had a really similar issue with my 2003 Audi A3 diesel. With some experience working on cars, I could tell the symptoms matched what you are describing, especially that constant preheating lamp and smoke issue. The engine preheat system was giving me exactly the same trouble. After taking it to a workshop, they diagnosed a loose connection in the wiring harness going to the control unit. The cable insulation had worn through, causing intermittent contact. Total repair cost was 95 Euro, which covered diagnostic time and fixing the cable connection. Your vehicle heater symptoms definitely sound familiar, but to help more specifically I would need to know: Current mileage on your A2, Whether any diagnostic codes have been read, If the ignition system problems occur more during cold starts, When was the last time the preheating unit was checked One thing to note, while the symptoms can seem dramatic, addressing wiring issues early prevents more expensive control unit failures down the line.

Just had my last service at 180315 KM. The preheating unit on these A2s is known to cause problems. After checking fault codes, it was indeed the defective part in my case. The control unit had to be replaced together with two glow plugs in the ignition system. Total repair cost was around 450 Euro at a qualified workshop. The vehicle heater now works perfectly and cold starts are smooth again with no smoke issues.

Thanks for the update on your A2 repair. My A3 eventually needed a similar fix, the temporary wiring repair I mentioned earlier only lasted about 6 months before the entire preheating control unit failed. Like in your case, the electrical fault turned out to be more severe than initially diagnosed. Ended up replacing the car preheater control unit and all four glow plugs as a preventive measure. My repair bill came to 520 Euro, slightly higher than yours since I went for a complete glow plug replacement. These car electronics can be tricky, what starts as a simple wiring issue often reveals deeper problems with the preheating system. Good to hear your cold starts are working properly now. After my repair, the smoke during acceleration completely disappeared and the check engine light hasnt returned. These heating modules are definitely a known weak point in our models, but at least the fix should last several years when done properly.

Looking back at this repair job for my 2001 A2, it was definitely worth addressing the electrical fault properly instead of trying cheaper temporary fixes. The complete replacement of the heating module and glow plugs in the ignition system solved multiple issues at once. The total cost of 450 Euro might seem steep, but considering the defective part was causing ongoing problems and potentially damaging other components, it was money well spent. The vehicle heater now performs flawlessly in all conditions, which is especially noticeable during cold starts. For anyone facing similar preheating unit problems, I recommend getting a proper diagnostic scan first, it saved time and prevented unnecessary parts replacement. My workshop experience confirms these control units are a common failure point, but once properly fixed, the system works reliably again. The elimination of smoke during acceleration and the properly functioning ignition system proves it was the right call to replace both the control unit and glow plugs.