Found the coolant level like this before the next expedition, got spooked, bought the coolant and distilled water on the way out (there was no time to top up back then), the expedition was uneventful, and I promptly forgot about this until today when I was making preparations for the next expedition. It's been over a month since. The level hasn't changed discernibly. 5800 miles on the vehicle, 14 months old, never complained about anything other than low battery after two days of camping.

First question: how low did you folks see your coolant go before the vehicle started complaining? Based on all other vehicles I've had, they're usually very good about that, I'm surprised this one didn't make a peep.
Second question: the JLR coolant jug mentions that while at 50% the boiling point is 129°C, at 70% it is 135°C, so I'm thinking whether I need that here where the surface temperature can easily reach 70°C (158°F). Some heavy mountain climbs ahead, wonder how much is enough.

Any words of wisdom?

 

I would keep mine at the max level of the tank. You may have a tiny leak if you are having to add coolant. Just keep your eye on it. I had the same issue with a 2023 Defender and after several visits to the dealership, they discovered a very small leak at the water pump.

 

Mine likes to stay at the level it chooses, which is usually below min. Got a low coolant warning message for the first time last week ( first time in 6 years).

startled, I added some coolant. Maybe a cup or so and she’s fine. I looked under the car to see if any new drips appeared and found maybe a slightly leaky oil drain for the turbo and a leaky rear diff.

you could use some uv dye to try and find the leak

 

Has anyone had issues with the coolant low level warning? Mine indicates low level warning intermittently, yet when I check the level, it is spot on at MAX level. It would seem to be a faulty sensor, but it apparently is built into the coolant reservoir and is not able to be replaced as a separate unit, requiring replacement of the coolant reservoir tank. Wondering if this has shown up with any frequency in other owner’s Defenders. Mine is a ‘22 110 P400. If anyone has done a replacement, please recount your experience here as to difficulty, tools and time spent. Thanks in advance for any feedback.

 

Yes - I had this exact issue on my 2022 110 SE P400 in mid 2025. Dealer replaced coolant reservoir with integrated sensor and it resolved the issue. Fortunately mine was still under factory warranty at the time.