Clio 172 will not start - immobiliser, UCH and keys issue suspected

[lenny2000]

Hello! So I’ve done a hefty amount of research on the forum but nothing has been able to point me in the right direction of finally fixing this issue I have. Going back a few months I had some electrical issues with my 2003 clio 172 sport (lights and windows playing up). I put this down to a bit of a faulty UCH. After which I sent off my UCH to RenBreakers where they would take the data off mine and put it on a new one for me. Upon installing the newly coded UCH, the problems seemed to be fixed but after a few starts, the car just stopped cranking all together. The immobiliser light would stay solid red and the car would not attempt to turn over. Since then I’ve tried recoding the key and recoding a brand new key. This didn’t fix the problem although sometimes right after recoding the immobiliser light would switch off as it’s meant to, turn the key… no start, and then it would go back to flashing red. I’ve ruled out any mechanical issues as when the immobiliser was off I gave the starter a positive feed and the car started right away! I’ve spoken to Renault and they say the UCH may not be communicating with the ignition computer but even they said a new ignition comp and recoding may not be a guaranteed fix. I’m in a sticky spot because the car is immovable, I can’t get it to any Renault specialists, I don’t want to take it to Renault for £££ reasons hence the post on here. I’m really really stuck and looking for any help I can get to fix this! Any replies are greatly appreciated and hopefully one of you has been in a similar spot and found a way out.

 

[hopgop1]

I'd check the common electrical fault areas first, check the big white connector in the engine bay is entirely free of corrosion, gearbox earth strap, could try putting a jump lead from the negative on the battery to the body to try and rule out a bad earth issue.