Hello there. 

I own a 2004 Octavia 4x4 turbo and have noticed a coolant temperature fault, the car sits at 90°C but when I switch on the climatronic the temp drops to 60°C and in some cases brings on the eml. I replaced the coolant temp sensor but this didn't cure the problem, could it be the climatronic unit that's at fault?

Weak thermostat?

 

My fabia does the same just no eml 

I made the mistake of not changing the stat at the last cam belt change.

Was ok for a year or so then went tits up

 

I would be in the thermostat camp on this, as climatronic should run fans all the time. Looks like the engine is overcooling itself.

 

You could confirm this, if you know someone with VCDS to log your actual engine temps while you drive and use the climatronic.

 

Just out of interest, was the coolant sender an oem or pattern unit?.

15 hours ago, kentphil1 said:

I would be in the thermostat camp on this, as climatronic should run fans all the time. Looks like the engine is overcooling itself.

 

You could confirm this, if you know someone with VCDS to log your actual engine temps while you drive and use the climatronic.

 

Just out of interest, was the coolant sender an oem or pattern unit?.

Genuine sensor from tps.

On 13/03/2020 at 20:51, Kenny130pd said:

coolant temperature fault

Another one who thinks this is a thermostat fault. I'd go further than most, and say that I suspect the thermostat may have broken up or been removed, resulting in the engine being over-cooled. That said, replacing the thermostat should lose you maybe a cupful of coolant.

Hi there, thought I'd better update this thread. Decided to go all out and replaced the timing belt and water pump, along with the tensioners and auxiliary belt. I also replaced the plastic water pipe connections with alloy ones, removed the SAI and fitted a new thermostat. The car now sits at 90°C with no fluctuations.