MOT failer HELP please

Hi All

My freelander failed MOT on Emissions, it is a 98 1.8k engine, head gasket is all ok, Changed Cat, engine oil &filter spark plugs and air filter. took it back inthis pm to breatherliz once more, no change at all, fast idle at between .550 and .600,(should be <.300) with idle at .561 (<.500)

machanic told me to fit a Bosal cat and a Lambda sensor, as i got a cheap cat of onlineautomotive.co.uk, said they are waste of time head been fine, he also put the sniffer in the collant pot, no co2 in there so all good head gasket wise.

Found this site for cat leisureshack.co.uk who do bosal cats at £75 delivered, does anyone know where i can get a Lambda sensor, seems to be loads out there but all diferent prices, could any one reccomend one, though i'm on a tight budget!!!!!

thanks for any help

Hi all anyone know what a good make of Lambda will be for a 98 1.8 engine please, ned to order one today, and could to with know if the NGK is a good one??

cheers in advance

Used an NGK one in my K1.6 Rover - seems ok. As long as it switchs properly any one will do, you may have to join the connector off your existing one to the new one's wires if it's a generic type. (most cheaper ones are) If it comes with a make specific connector fitted it probably ain't that cheap.
An effective CAT's the main problem keeping the K series in spec - it's was close to todays limits even when it first left the factory.