# Urgent Help! 2nd time EGT sensor failure, need to get rid of it!



## surfo (Jan 6, 2006)

Hi guys... long time since I don`t post here, hope you all are doing great!!..

right now I`m having problems with a Seat Leon Cupra R 225 (same that the TT 225), it`s the second time that the Exhaust Gast Temp sensor fails and it`s DAM EXPENSIVE!!!... we already have an external EGT gauge to monitor them. 

So the real question is: "is there a way to set a Fix signal so the ECU reads a desired Temp?"... 

better explained... let`s suppose that at 3.5v temp signal equals to 800ºC and is the EGT that the external gauge is reading under high boost at the track... (is just an example)... how can I trick the sensor connector so I can get rid of this sensor for ever...

What diode do I need, what potentiometer do I need? how can i check this?...

something like the MAP clamp trick... :screwy:

I`m just sure about doing this "trick" because we can monitor A/F, EGT, etc. 

Picture of the EGT sensor 










Best Regards!!:beer::beer:


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## surfo (Jan 6, 2006)

Gurus come to me!


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## warranty225cpe (Dec 3, 2008)

Uh.. How do you know your not too hot and burning it out? My appologies if I missed it in your post.


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## Doooglasss (Aug 28, 2009)

Well looks like you're working with a BEA motor code? If so I believe that sensor is essential to fueling. The car determines which fueling map it's going to use due to temperature that sensor reports back. On older cars it is a calculated value off the primary 02's feedback- I'm not sure if your car will replicate that calculation.

If you do a 3rd gear WOT pull do you get the desired AFR's ?

What software are you running?


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## Marcus_Aurelius (Mar 1, 2012)

The sensor can be resistored to fool the ECU into thinking that it's still there. However, like Doug said, there are ecu map switchovers that are dependent on that signal. One important one that comes in mind is the full load lambda map that relies on a preset EGT threshold to be interpolated. (BTW Doug, the non-EGT AMU use full load lambda map as well but use the calculated value that is based on primary O2 temp signal. It works pretty well and is very accurate, once you know the O2 sensor range of operation, it is like having an EGT probe just at a different spot. I use the data with great consistency all the time.)

OP, If you don't mind "locking" the fueling in the full load lambda map, you could resistor it to stay pass the preset threshold in your file. IMO, unless the car is a track car that could careless about drivability, it is not the best idea. I couldn't tell you exactly what resistor to use because the EGT sensor voltage signal is unknown to me, but like I said it is possible to lock it in full load lambda mode and delete the sensor from the loop.


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## Doooglasss (Aug 28, 2009)

Yeppp I was trying to tell him that the older (AMU/AWP) ECU's try to calculate off the WB 02 and I don't know if the BEA ECU does that (as a backup) or soley relies on the EGT sensor- that's why I asked what his fuel trims look like under a WOT pull without EGT- to see if it's still doing it.

By the way, Tapp opened up access to the base fueling map (map used before EGT threshold is exceeded). I'm able to get my car to run at 1.2 lambda cruise/idle now.


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## spyrstas (Sep 6, 2009)

I've been wanting to do the same thing to my Leon Cupra. Btw on our cars and the S4's the ecu only see's two temperatures from sensor. One temp is normal conditions and the other temp the ecu believes that the car is burning up and then sends more fuel to cool it down. Only the rs6's have the full range egt sensors. I just installed a used(working) sensor but it's confusing me somewhat. With no sensor connected the 3wire show- nothing, ground, 13.8v. When connected and car running it shows(in the same order) 13.8v, ground, ~0.70v. This was with the car being cold~60c water temp, and no fault codes. I don't know what size resistor to use, anyone shed a little more info on how-to?


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