Seat Leon 1.9 TDI BXE - Engine Temperature keeps dropping

Sep 18, 2020
20
1
i have an issue with my Seat Leon 1.9 TDI 2008 retaining engine temperature.

I have performed an EGR delete using a blanking plate and it appears the warm up time now is now significantly slower than it was before.

Once the car reaches 90 (without the heaters on,) if I'm sat idling and then put the heaters on, the temperature starts to drop and doesn't stay at 90.

As soon as i turn the heaters off the temperature then rises back up to 90.

I have changed my thermostat to a Gates one however, i still have this issue.

Could it be the Coolant Temperature sensor that is faulty?
 

RADIOTWO

Active Member
Mar 6, 2018
489
94
North Derbyshire
i have an issue with my Seat Leon 1.9 TDI 2008 retaining engine temperature.

I have performed an EGR delete using a blanking plate and it appears the warm up time now is now significantly slower than it was before.

Once the car reaches 90 (without the heaters on,) if I'm sat idling and then put the heaters on, the temperature starts to drop and doesn't stay at 90.

As soon as i turn the heaters off the temperature then rises back up to 90.

I have changed my thermostat to a Gates one however, i still have this issue.

Could it be the Coolant Temperature sensor that is faulty?
It will do as the cooling systems are noe very efficiant nowadays so as it shoud be
 

R3k1355

Active Member
Oct 30, 2014
1,787
251
Yorkshire
There's usually an EGR cooler that takes some of the heat out of the exhaust gas before it's stuck back in the engine.

With the EGR blocked that heat isn't there, probably why you're noticing the temp dropping.
 
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martin j.

Active Member
Feb 11, 2007
1,996
891
Fife
I’ve noticed with a few diesels I’ve driven that idling allows the temps to drop and using the heater wii speed this up.
 
Last edited:
Sep 18, 2020
20
1
There's usually an EGR cooler that takes some of the heat out of the exhaust gas before it's stuck back in the engine.

With the EGR blocked that heat isn't there, probably why you're noticing the temp dropping.

Ah ok that kind of makes sense. Would you recommend blanking off the EGR cooler too?
 

smutts

Active Member
Apr 12, 2020
372
188
The temp gauge lies anyway.
The computer sticks the dial at 90C for real coolant temperatures from about 70C to 110C ish.
Stupid really.
Try it with an OBD reader.
 
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