Help! 17705 fault code, no boost control, and pre-detanation

mty12345

Active Member
Jun 17, 2011
3,959
577
bristol
The map quite possibly, but it's unlikely to be the ECU in my experience mate, they tend to either work or they don't. There is a useful link here in terms of running logs with VCDS/vagcom. https://www.goapr.com/support/datalogging.php

If you do a few runs logging both the boost and the fueling and post them up here, then that will hopefully point you in the right direction.
 

Leon20vt4

Active Member
Oct 21, 2018
939
683
Don’t get an eBay VAG COM. I know the real one is expensive but you can get legit ones for 100 quid or so


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Oct 21, 2019
13
1
My dad has a cheap ebay vag com lying around ill give that a go first as it wont cost anything if not then proper one it will have to be lol. I found out today aswell my coolant fan isn't kicking in on hi speed I have twin fans and both run with air con on slow speed. Not sure if it's linked to the boost issue but could be the pre detonation issue I have. I have checked the fuse on the battery and its OK and I have changed the coolant temp swith and the rad fan switch and swaped to another relay or resistor box under the chassis leg on the nearside. Still doesn't kick in. The fans work on high and slow speed if you put power down the connector from the rad fan switch. It has 3 terminals. One is constant live. And other 2 are earthed. If you put power down the either of the 2 earth's then you get high and slow speed depending on which one you put to live. It's sounds like the box under the chassis leg has a relay in it because it clicks when power is put down the wire that controls high speed on the rad fan switch connector. This car loves playing up I tell you. What else could this be. It was a long and quite expensive day again today changing many new parts to help the old girl. Map? Ecu? Something else? Anyone?, haha thanks for the replies guys.