Renault Clio had been airbag on for about 6 months, but mot next week meant I had to sort this one out. Tried the under seat cable trick, no joy. Checked the ECU and there was some sign of liquid but not in the ECU itself. Took it to a garage for diagnosis and they use Renault Can Clip cleared the faults (25 quid), only 2 errors remaining were these:
B1036: passenger side impact sensor
B1035: driver side impact sensor
Turns out this is just a little plastic unit bolted underneath the seat (directly below door) with a cable connected. I went to the scrappy and got 2 of these (10 quid each), replaced old with new in 10 minutes (unhooked battery first) and the lights went out straight away, no need to do a further reset or anything.
My advice here would be if sorting the cables under the seat doesnt fix this issue, get it diagnosed. In my case I was ready to buy a whole new ECU, turns out that wouldn’t have helped at all.
Anyways, hope this info helps someone, all the best!