Failed MOT on emissions. how many lambda sensors?

[rsvmad1]

The clio has done me proud, only failed on a couple of bulbs, lambda sensor, and emissions.. I knew it would fail emissions as the sump plug is rounded so was unable to service until my m8 can get the sump plug out for me, and the MOT tester recommended I should take off the big back box, fit standard, and take off the big cone air filter and fit a standard air box, and use a petrol treatment (emissions in a can as he calls it lol)

How many lambda sensors do clio 1.4`s have? just one???????

 

[bmh.01]

Two, your only really interested in the precat one though.

 

[rsvmad1]

Two, your only really interested in the precat one though.

The one after the cat on the middle section?

 

[JackJack]

The one before the cat.

 

[rsvmad1]

The one before the cat.

is it hard t get too? the cat is at the back of the engine, or am I wrong? cheers