Hi
Have an 03 l322 3.0 diesel
Once the engine reaches temprature after accelerating and decelerating the message check coolant level comes up.
I have checked it numerous times and the level is correct.
Any ideas ?

Check the SG (specific gravity) of the antifreeze coolant.
You get a low level warning if it becomes diluted by topping up with water.

Mike. G reg 2.5VM Vogue Portofino red 1991- 1999
V reg 2.5td P38 Rioja red 1999- 2006
53 reg td6 Vogue Oslo blue 2006- 2015
11 reg 4.4 TdV8 Vogue SE. Baltic blue 2015- date.
https://www.fullfatrr.com/forum/topic56162...tty+affair

Sounds like a faulty level sensor or expansion tank if the level is correct.
The sensors can play up & the disc built within the expansion tank can cause the warning to appear.

There are many threads on here to view.

I tried the sensor first (cheapest route), but eventually bought another expansion tank complete with another new sensor & now all is fine.