hi Just failed MOT on Emissions, the car is 93 wrx import which still has standard exhaust apart from scoobyworld ninja backbox. here are the test readings.

Fast Idle Test :

fast idle Co vol% 6.34 Failed
F. Idle HC Volppm: 313 failed
Lambda : 0.839 failed

2. Fast Idle Test :

Fast idle co % 0.66 failed
Fast idle HC ppm: 223 failed
Fast idle Lambda 0.983 Passed

Natural Idle Test :

Idle co vol%: 0.44 Passed.


any idea's what the problem could be?

thanks

 

Mine recenlty failled an MOT due to emmissions, turned out to be a leaking turbo gasket.

 

Your Lambda sensor looks like its shot. Choices are get one from Subaru @£280 last time I checked.
Or get a three wire sensor (red, white and black wires) for a UK turbo and join them. The wires are titanium so you can't solder them. Crimp connectors and heat shrink sleaving works well.
Or get a second hand one from the breakers in exchange and mart.
Or I think lucas do a universal one. If you do a search you should find the part number SEB 230 rings a bell but I'm not sure.
You will also have to remove the surrounding heat shield to get at it, which is not as hard as it looks.