Hi there. I have a freelander2, 2011 model, while climbing a steep hill (normal road) engine overheats very quickly without any warning and the coolant spills over fully. I Have changed the sensor of the FAN UNIT, still the problem persists. Request for some help in this area to solve the problem.

Blown cylinder head gasket? do a compression test and check for water in the oil. 2013 FL2 XS.
Defender 90 300 TDi.
Defender 90 300 TDi CSW.
1964 MGB Roadster.
1944 Willys MB "Jeep" with bullet holes. (gone)
17 hand Irish Drought Thoroughbred (mostly lame)
Nagging Old Boiler.

Mahatma Gandhi said if there is an Idiot in power those who elected him are well represented

What engine?
The fan doesn't have a dedicated sensor. The ECM controls the fans, based on engine temperature and current load. Also the fans come on if the AC is active.
Have you checked the fuse for the fans? Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Are the fans working? Jules

This link has a good explanation about the Fan.

https://www.freel2.com/forum/topic36668.ht...eck+cheque

And this link is to Fan / Heater related topics

https://www.freel2.com/forum/search.php?se...rch_time=0

You can try your own search on the forum. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)