G35 Overheating Nightmare: Multiple Warning Lights Mystery

Hey there! I had some experience with a similar issue on my 2004 Infiniti M35. The symptoms you're describing sound exactly like what I dealt with last year. It turned out to be a faulty cable connection to the water pump. The plug was corroded and wasn't making proper contact, causing the pump to malfunction. Took it to my trusted mechanic, and they diagnosed it pretty quickly. The repair cost me about 155€ (including labor), and it fixed all those issues the overheating, warning lights, everything. Before I can help more specifically though, your exact model (G35, G37?) Current mileage Are you losing coolant rapidly or just gradually? Any unusual noises from the engine bay? Let me know these details, and I might be able to offer more targeted advice!

Thanks for the detailed response! I've got the G35, currently sitting at 161514 KM, and I just had it serviced last month. The coolant loss is pretty gradual I'd say I need to top it up every couple of weeks or so. No weird noises from the engine bay, thankfully. Your water pump situation sounds pretty similar to what I'm experiencing. Did you notice any sweet smell from the engine bay before you got it fixed? I'm hoping it's just a connection issue like yours and not something more serious. The fact that you fixed all those warning lights with one repair gives me some hope!

Hey again! Thanks for the follow-up, and good to hear from you. Yeah, my M35 was around 155,000 KM when I had those issues, so pretty close to your mileage. Now that you mention the sweet smell yes, actually! I did notice a slight sweet smell, but I didn't think much of it at first. That's typically coolant, which makes sense given the faulty pump connection. In my case, the coolant was leaking very slowly through the corroded connection point, causing that sweet smell. You know what's interesting? The gradual coolant loss you're describing (every couple weeks) is almost exactly what I experienced. Since you've just had it serviced, did they check the water pump connections? Sometimes these things can be missed during routine maintenance. I'd really suggest getting those connections checked first before looking into more expensive repairs. My mechanic showed me the corroded connector after he replaced it it was pretty nasty! The fact that you're not hearing any unusual noises is also a good sign when my water pump was going bad, it started making this weird whining noise right before it completely failed. Let me know what you find out! I'm curious if it turns out to be the same issue. These Infinitis are great cars, but they do have their quirks with the cooling system.

Thanks so much for all this information! It's really reassuring to hear your experience was so similar to mine. You're right I don't remember them specifically checking the water pump connections during the service, so I'll definitely have that looked at first. I'll call my mechanic tomorrow and mention what you found with your M35. The similarities between our situations are pretty striking same mileage range, same gradual coolant loss, and even that sweet smell. I'm actually feeling pretty optimistic now that it might be a relatively simple fix like yours was. I'll update you once I get it checked out. Really appreciate you taking the time to share your experience in such detail!