Discovery Diesel Overheating: Bad Aux Pump Warning Signs

Hey there! I have some experience working on cars and went through something very similar with my 2020 Land Rover Defender diesel last year. Those symptoms definitely sound familiar, I had almost the exact same issue. In my case, it turned out to be a faulty cable connection to the water pump control unit. The repair set me back about 225 Euro, but it fixed all those warning lights and overheating problems completely. My regular workshop spotted it pretty quickly once they did the diagnostics. Before rushing to conclusions though, what's your current mileage and have you noticed any coolant leaks or unusual noises? Also, when did these symptoms first appear? This info would help me give you more specific advice based on my experience with Land Rovers. Would definitely recommend getting it checked ASAP, these issues can get worse if left unchecked. Have you tried contacting any specialists yet?

Hey, thanks for the detailed response! My Discovery has 140755 KM on the odometer and just had its service last month. No noticeable leaks on the ground, but I've started hearing a slight whining noise when accelerating. The symptoms began about a week ago, starting with just the check engine light, then progressively got worse. Your experience with the cable connection issue is really helpful, could definitely be something similar. I'll get it checked out at the workshop tomorrow. Did your Defender also have that whining noise before you got it fixed? Just trying to figure out if I'm dealing with the same problem here. Really appreciate the help! These issues can be quite stressful, especially with a relatively new car.

Hey again! Yes, my Defender actually had that exact same whining noise, it's what really got me worried in the first place! Mine started pretty much the same way too, first the check engine light, then everything else followed. The mileage is pretty similar too, I was at around 135000 KM when it happened. The whining noise in my case was definitely connected to the cable issue I mentioned before. It's basically because the pump wasn't getting the right electrical signals, so it wasn't running at the correct speed. Once they fixed the connection, that annoying whine disappeared completely. Quick tip from my experience, when you take it to the workshop tomorrow, make sure they check the entire electrical connection pathway, not just the pump itself. My mechanic initially only looked at the pump and couldn't find anything wrong, but then traced it back to find that damaged cable connection. Let me know how it goes at the workshop! Really hope it's the same straightforward fix I had. These Land Rovers are great cars, but they can throw some interesting problems at us sometimes! Keep us posted.

Thanks so much for all this detailed info! Really appreciate you sharing your experience, it's actually quite reassuring to hear your Defender had such similar symptoms. The bit about checking the entire electrical connection pathway is super helpful, I'll definitely mention that to the mechanic tomorrow. You're right about these Land Rovers throwing interesting problems at us! But knowing your issue was fixed with a relatively straightforward cable repair gives me hope. I've already called the workshop and booked it in for first thing tomorrow. Will make sure they do a thorough check of all the connections, not just the pump itself. The similarity in our situations is quite striking, from the whining noise to the progression of symptoms and even the mileage. Fingers crossed it's as simple as your repair was! I'll definitely update the thread once I know what's going on. Thanks again for taking the time to help out, it's made me feel a lot less stressed about the whole situation!