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URGENT Fiesta zs 2001 lambda missing

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Ive got a big problem, ive got a fiesta with some mods from a guy, the post cat or the downstream oxygen sensor is missing and i cant find the plug for it under the bonnet. the car gets 180 miles per 40L of fuel, and emissions are not pass worthy. but i cant seem to find a second sensor connection anywhere i look. could someone tel me if this is normal or must there me a secondary lambda? ive been searching forever now and cant find similar issues. im struggling to find out whether i need to buy and rewire a sensor to the ECU or is the connection hidden somewhere. 

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I don't have a fiesta but the principal is the same on my focus. If you have moded car ie a remap of some sort the Lamda sensor post CAT could be/probably is mapped out ie its been switched off to stop the EML light showing on your dash (as is mine).Mine is left in place ( I have a sports CAT)but is not recognised by the ECU at all and is part and parcel of the remap. Who ever had your car before you if mapped may have taken the lamda out and fitted a bung plug instead if that is the case that is how it supposed to be as the sensor is no longer used by the ecu and is normal for some remaps.The cable should/will be some where underneath probably tucked up in the wire loom  as if you wanted to put it back to a OEM map then you will need the Lamda  and decat replaced for this is that it may have a Decat (a pipe that looks like a cat )but is a straight through pipe fitted in that case is the reason it won't pass the emission test.If this is the case then you could fit a sports CAT that will put you emissions right .Other wise you need to get a friendly MOTer that will look the other way when testing.Putting the Lamda back in with a DEcat will not make any difference with emissions  but will effect performance .If you have no dash eml light on all the time  it is more than likely to be mapped out.Some people fit a CAT for MOT then take it off again when passed and refit the DEcat.Its all to do with performance of the engine.This is of course if the Fiesta actually has apost Lamda in the first place.If all the above is correct  you don't have a problem with the car until MOT time.Or if  VORSA do a roadside test and that is very unlikely

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