I'd read so many people having trouble with aftermarket sensors, I was assuming I'd need to go to the dealer. If the ECP ones are OK I'll splash out on a pair. £130 isn't too bad I guess. Beats £200 anyway.

OT - I bought the subframe bushes from that ebay listing, they're Febi, the same as G'n'S sell. I'm fitting them tomorrow. The guy that rents out the tool is only about 15 minutes' drive from me so that's pretty handy