Evening everyone, this is my first post here so I’ll try and keep it brief. Recently bought a 2008 C30 (2l Diesel R-Design), when I got it it ran fine although the battery was old and weak, long story short the battery eventually died completely so I’ve replaced it with a brand new one, however this seems to have triggered the immobiliser fault which looking over the forums seems all too common! No crank, nothing at all, the key unlocks and locks the car, removes the steering lock and activates all the power but nothing else, when trying to start it pops up with ‘immobiliser try start again’ and I can hear a relay clicking somewhere but can’t pinpoint where to be honest. Fault C326 is stored in the fault log on my OBD scanner. Checked all fuses, connections etc so all good there, so I assumed the CEM and ECU had lost sync due to the battery issue. Found a company who can re-sync them so they’ve been taken off the car and supposedly re-synced but I’ve had them back today and guess what, no start still and the C326 fault is still stored🤦🏻. Love data on the scan tool shows that the key is approved, start is approved but there is an issue with the ECM signal now apparently. I’m gonna send the CEM and ECU back to the company that did the re-sync but wandered if anyone had any more suggestions about what I could do to fix this issue as I’m at a bit of a loose end now, especially if this 2nd re-sync doesn’t work!

Thanks in advance!

p.s I’ve tried everything else I’ve seen on the forums such as locking and unlocking, leaving the battery off overnight etc and none of it has worked!