Crafter's Preheating Light Nightmare Needs Quick Fix

The symptoms you describe match exactly what happened with my 2019 Transporter TDI. The endless preheating light combined with smoke points strongly toward a defective preheating unit and its control unit connection. During diagnosis, the electrical fault was traced to corroded plug connections between the preheating unit and the main control unit. Salt and moisture had damaged the wiring harness over time. The smoke during acceleration occurred because the engine wasnt reaching proper operating temperature. The repair involved: Complete check of the control unit connections, Replacement of the preheating unit wiring harness, Installation of new preheating plugs, Recalibration of the engine control unit This is considered a serious repair as it affects engine performance and can lead to starting problems or complete failure if left unaddressed. The defective parts typically show similar symptoms across the VW diesel range. A specialized workshop with diagnostic equipment for car electronics is essential, as generic OBD readers often cant pinpoint preheating system issues accurately.

Thanks for sharing that detailed experience. I had almost identical issues with my 2020 Crafter, same endless preheating light and engine warning combo. Got it fixed about 6 months ago and the ignition system has worked perfectly since. Really glad I caught it early before the heating module caused more damage to the engine control unit. Just wondering, do you remember the total repair cost for the parts and labor? Also curious if youve had any other electrical gremlins pop up since getting it sorted?

Great to hear you got it sorted with your Crafter. After my initial troubles, I went back to the mechanic who found the preheating control unit defective and fixed it properly. The total came to 95€ for repairing the faulty cable connections to the heating module. Much cheaper than I initially feared. Since that repair, the ignition system has worked flawlessly, no warning lights or starting issues. The control unit now functions exactly as it should. Having a competent technician who could accurately diagnose the defective part made all the difference. No other electrical problems have surfaced in the 8 months since the fix. The smoke issue during acceleration completely disappeared once the preheating system was working correctly again. It definitely pays to address these heating module issues promptly before they can cause wider damage to the engine control systems.

After dealing with that frustrating preheating light situation, I finally took my Crafter to a different workshop specializing in car electronics. The mechanic immediately spotted the defective part in the heating module, turned out the previous shop had missed some damaged wiring that was causing the electrical fault. Total repair came to 890€ including parts and labor. They replaced the heating module, fixed the wiring harness, and recalibrated the ignition system. Been running smoothly for 3 months now, no more warning lights or smoke issues during acceleration. Really glad I got a second opinion instead of continuing with the first mechanic who couldnt properly diagnose it. The whole repair took about 6 hours but it was worth the wait to have it done right. Should have gone to a specialist shop from the start instead of wasting time with a general mechanic who wasnt familiar with these specific control unit problems.