G63 Check Coolant Message
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Joined: Jan 2007
Posts: 87
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From: USA
`22 G63
G63 Check Coolant Message
So over the past week or two I had been getting a "Check Coolant" message on the left of the instrument cluster screen on cooler morning startups or at the end of the day after the car had been sitting at my office. After probably 100 yards of driving the message would go away, every time, so I figured it was just slightly low coolant. Coolant temp on the gauge stays pegged right in the middle. Last Service was done in January at 13k miles and I now have 21k miles on the rig. It is a 2022 G63.
I purchased some proper specification coolant and just added it after letting the car cool down all night. I read the manual and filled it up as it explained. What surprised me is that it took about 3/4 of a quart which is way more than I had expected. Now the coolant level is correct per the instructions but it is higher than the Max line on the side of the reservoir (the lines are very hard to see which I guess is why the MB Manual says to look into the reservoir for market bar).
I am hyper sensitive to coolant problems since I had a blown head gasket in a Range Rover that caused massive issues. I thought the coolant system was a closed system and there shouldn't be a need to top it off. Also, if the level on the side of the reservoir is always over the Max line should I be concerned knowing that I followed the instructions? I have zero fluids leaking under the car in my garage so I don't think I have any leaks but what could cause a closed system to lose coolant?
Thanks for advice on this engine.
I purchased some proper specification coolant and just added it after letting the car cool down all night. I read the manual and filled it up as it explained. What surprised me is that it took about 3/4 of a quart which is way more than I had expected. Now the coolant level is correct per the instructions but it is higher than the Max line on the side of the reservoir (the lines are very hard to see which I guess is why the MB Manual says to look into the reservoir for market bar).
I am hyper sensitive to coolant problems since I had a blown head gasket in a Range Rover that caused massive issues. I thought the coolant system was a closed system and there shouldn't be a need to top it off. Also, if the level on the side of the reservoir is always over the Max line should I be concerned knowing that I followed the instructions? I have zero fluids leaking under the car in my garage so I don't think I have any leaks but what could cause a closed system to lose coolant?
Thanks for advice on this engine.
Last edited by a4ep; Nov 2, 2025 at 01:20 PM.
