Voyager Preheater Warning Light + Smoke Issues Fixed

I had a very similar issue with my 1998 Chrysler Voyager diesel last winter. The symptoms match exactly what you describe, persistent preheater light, check engine warning, and smoke during acceleration. After some initial troubleshooting, the workshop diagnosed a faulty connection in the heating module wiring. The vehicle heater control unit itself was actually fine. It turned out to be a corroded plug connection that was causing intermittent electrical faults in the ignition system. The repair cost was 95€ including diagnostic time. They cleaned the connections, replaced one damaged wire, and reset the system. The car has worked perfectly since then. Before jumping to replacing the entire control unit, I would suggest having the wiring connections checked first. These issues often stem from basic electrical connections rather than the car preheater components themselves. To provide more specific guidance, could you share: Any error codes from the diagnostic scanner? Does the issue occur more frequently when the engine is cold? Have you noticed any changes in starting behavior? Are there any other electrical issues present?

Thanks for the detailed response. After checking my error codes at home, I got P0380 and P0671. The problem is definitely worse during cold starts. The engine takes longer to turn over compared to before. Mileage is currently at 53019 KM. Last service was 2 months ago where they only did an oil change and basic inspection. Since your post, I also noticed the car electronics seem a bit inconsistent, dashboard lights occasionally flicker when starting the engine. Given this additional info about the electrical symptoms, Im starting to think youre right about checking the wiring connections first. Just hoping its not a more expensive heating module failure. Worth mentioning the smoke has gotten slightly worse over the past week, especially during morning starts. Getting concerned about potential damage if I keep driving it like this.

Based on those error codes and the flickering dashboard, your symptoms sound nearly identical to what I experienced. The smoke getting worse is particularly concerning and matches the progression I saw before getting mine fixed. The P0380 and P0671 codes typically point to the preheating circuit, but in my case and likely yours, the root cause was deteriorated wiring rather than a failed heating module or control unit. The increasing smoke during cold starts is a classic sign of incomplete preheating due to poor electrical connections. A key diagnostic step the workshop did for my Voyager was testing voltage at the preheating unit connections while the engine was cold. They found voltage drops indicating bad connections, which explained the inconsistent preheating and resulting smoke. Since your mileage is similar to what mine was, youre likely dealing with the same age-related wiring degradation. The flickering dashboard is another telling sign, it suggests the electrical issue affects multiple systems, just like my situation. I would strongly recommend getting the wiring inspected soon. Continued driving with incomplete preheating could lead to carbon buildup and potentially more expensive engine repairs. The repair should be relatively straightforward if caught early, my fix only required cleaning connections and replacing a small wiring section near the engine preheating system. Would you like specific details about which wiring areas were problematic in my repair? That might help you discuss the issue more effectively with your workshop.

Thanks for sharing your experience. The wiring details would definitely be helpful before I visit the workshop. Your situation sounds nearly identical to mine, especially with those electrical symptoms. Going to book an appointment tomorrow to have them check the wiring connections first. I'm keeping track of when the smoke appears worst, mainly first 5 minutes after cold starts. Wrote down all the symptoms including the flickering dash lights to show the mechanic. Really hoping its just corroded connections like in your case and not a complete preheating unit replacement. The car is still starting but Im worried about causing more damage. Think Ill limit driving to essential trips until I can get it checked. Those voltage tests you mentioned sound like a good starting point for diagnosis. Quick question, after they fixed your wiring, how long did it take for the smoke and starting issues to completely clear up? Just want to know what to expect if they find similar problems with mine.