jaguar xf supercharged 2009 when the gear change between the 3rd and 4th gear its sleeps and the fault comes on . if im on D gear . if im on S gear its a bit better if im on S gear with race mode on its almost ok .i can go down from 4th gear to 3rd gear no problem at all, but from 3 to 4 it sleeps

 

Sounds like you are low on transmission fluid. Check your fluid level. If not try to reset the transmission. If all that doesn't work then you might have worn clutches

How many miles on the vehicle?

 

my car have 65000 miles on it or 105000km , we try to reset the transmission at the jaguar end up it was worst then before couldnt drive anymore they tried to fix it 3 to 4 times and i left the dealer with a 600$ bill with a car worst then before . they told me i need a new tranny 15000$ (seriously ...)
the only thing i found weird is that i had the exact same problem with a bmw 335 2007 and a guy really fixed my problem by flushing the oil , replace a little gasket that looks like a donut and the remap the tranny and it was just perfect

 

That's exactly what it sounds like. A pressure leak. There are little tubes that are in the tranny. The little plastic block also will crack and leak. Have them replaced and see what happens.

 

how much do you think it could cost to do that

 

No idea what it costs. But it would be much cheaper to have it done at a tranny shop. Jag dealers will charge you an arm and a leg and maybe even more. I did mine myself and the parts only cost a couple hundred dollars.

 

Did you find a way to fix the problem?

 

[QUOTE=croco;1794170]Sounds like you are low on transmission fluid. Check your fluid level. If not try to reset the transmission. If all that doesn't work then you might have worn clutches

How do you reset the transmission fault light?

 

What is the code? Has it been repaired?
Just clearing the light usually won't help anything.

Most faults that deep in the car require the factory software SDD.
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Hi keeganmr7 - the thread is from 2017...

Easy to do that by mistake - but prob too late for suggested fixes for the OP now!