Galant's Multiple Warning Signs: Coolant & Module Mystery

Hi there! I had some experience with a similar issue on my 2004 Mitsubishi Lancer Diesel (I'd say I have low experience with cars, but I've dealt with a few issues over the years). The symptoms you're describing sound exactly like what I went through last summer. It turned out to be a faulty cable connection to the water pump. I took it to my local mechanic, and they diagnosed it pretty quickly. The repair cost me around 155€, which included replacing the damaged plug and fixing the connection. Before throwing parts at the problem, could you share: How long has this been happening? Have you noticed any coolant leaks under the car? Does the temperature fluctuate or just stay high? Feel free to ask any other questions. Hope this helps!

Thanks for your input! Yeah, these issues started about two weeks ago. I've had the car serviced regularly (last service was at 130062 KM), but this problem came out of nowhere. I haven't spotted any obvious coolant leaks under the car, which makes it even more puzzling. The temperature gauge seems to fluctuate, it'll be normal for a while, then suddenly spike up. Your water pump theory might be worth checking out. Did your temperature gauge behave similarly before you found the issue? Just trying to figure out if I should take it to my mechanic or if there's something I can check myself first.

Hey again! Yeah, when I had my Lancer, the temperature gauge behaved exactly like what you're describing, those unusual spikes were giving me anxiety every time I drove! In my case, before finding the faulty water pump connection, I actually tried checking a few things myself. First, I inspected all visible coolant hoses and connections (while the engine was cold, of course). The frustrating part was that I couldn't see any obvious leaks either, just like your situation. When my temperature was fluctuating, it would stay normal for maybe 15-20 minutes of driving, then suddenly shoot up, especially in city traffic. Based on what you're describing, it sounds eerily similar to my experience. I did try topping up the coolant at first, thinking it was a simple fix, but it kept disappearing. That's when I knew something wasn't right. Since you mentioned your coolant keeps dropping too, I'd honestly recommend getting it checked by a mechanic soon. These symptoms are too similar to ignore, and in my case, waiting would've probably caused more expensive damage. One quick check you could do though, try looking at the coolant reservoir when the engine's cold vs. when it's warm (but not hot!). In my case, I noticed the level would drop significantly when warm, which helped the mechanic pinpoint the issue with the water pump connection. Let me know if you want me to explain anything else about what I went through with my Lancer!

Thanks so much for sharing your experience! That's really helpful information about the coolant reservoir check, I'll definitely look into that tomorrow morning when the engine's cold. It's reassuring to hear that your symptoms matched mine so closely, and that it turned out to be something fixable like the water pump connection. I think I'll take your advice and get it to my mechanic next week. You're right about not wanting to risk more expensive damage, especially since these Galants are getting harder to find parts for these days. The fact that you had such a similar experience with your Lancer makes me feel a bit better about the whole situation. I was worried it might be something major with the engine, but this gives me hope it's just a connection issue. I'll keep an eye on those coolant levels like you suggested and hopefully, it'll be as straightforward a fix as yours was. Really appreciate you taking the time to share your experience!