Intermittent short-term dash control + rear light failure

Engine size?
fuel type?

It's 1.6 petrol.

There's a known fault with these.
water gets into the wiring harness multiplug under the bonnet,
Near the right shock top looking from thr front.
surprised your mechanic didn't check his AUTO DATA section for known faults.
check that first.

Sorry for late response - many thanks for this. Car still with main Vauxhall dealer but they're scratching their heads + they've spoken to manufacturer who says they're at a loss too! Thought prob could only be with a partic unit (cost £600) but when they fitted it, the car wouldn't even start! Will ring them & pose your suggestion but must say that the issue has occurred during prolonged dry weather!

I have a 2002 vauxhall zafira with the exact same problem.
Mechanic has checked for the known problems and fuse box etc but can't seem to put his finger on it.
Usually a small bump or hard break can trigger or undo the symptoms. Definitely feels like a loose connection but even the pros haven't been able to find it.
Didn't take it to dealer as the proposed quote was something like 75% of the value of the cars current market value.

So any help or guidance much appreciated.

Ayoubtt, sorry to hear you've got the same. Main dealer thought they'd solved it by replacing some iffy fuses but it recurred before we collected the next day! They replaced a unit under bonnet that they said all problem issues have to go through. They couldn't get the car to work at all - so it wasn't that! They then said the only other thing they could try was to replace a 2nd unit - if that didn't work they were totally at a loss & would have to return the car with the issues! They used a 'donor' part as a test, from another Zafira who's alarm kept going off > my issues didn't recur for the 4 days I drove with the donor part. I then authorised them to order & fit a new unit & it seems to have done the trick. My total bill was £600 which is a lot but much cheaper than me having to replace the car. I do have to take the car back this week because my 06 car is part of the national recall over the problem highlighted on Sky News & Watchdog last week where some cars have gone up in flames due to something going wrong behind the glovebox. The new parts, to be fitted free of charge, were expected to be delivered to my local main dealer on Wednesday. If it'll help, I'll update on Wed with the names of the 2 units that they replaced.

What was the 2 units they used because I have the same issue with my Vauxhall zafira.