Lambor sensor position ?

[Domo2106]

While cleaning my engine bay I noticed my lambor sensor is right up by the turbo I have a sports cat fitted with 2 ports for the lambor sensor one up by the turbo where it's currently fitted and another after the cat near where the center section joins am I right in thinking the lambor should be installed after the cat ? It's a 2002 bug eye sti also it only has 1 lambor sensor is that right as my old 2005 wrx prodrive had 2 ?

[Scott.T]

Should have 2 lambda sensors. One in the header and one at the bottom of the downpipe.
The ECU measures the reading between both. The 2nd one would detect and flag a CAT Efficiency error if there was no cat.
Therefore I would expect yours to log a Cat efficency error if it is mounted pre-cat.

If it isn't, then either :
you have a lambda in the bottom of the downpipe
Or
you have one in the header and one in the top of the downpipe and the remap has deleted/disabled that code

As mentioned above the correct configuration is a one in the header (pseudo wide band) and one in the bottom of the downpipe (which I beleive is a regular narrowband).

[Domo2106]

I haven't checked the headders will have to get it back up on the ramps again tomoz would a cat efficiency error trigger the eml ? It also seems to be using a lot of fuel I'm struggling to get 200 miles to a full tank