2004 Vauxhall Corsa failing emissions during idling

Could try changing the engine temp sensor. Could also get car scanned to see if any faults are showing...

Might help if you posted the FULL gas analysis for the tests.

i would check for vacuum leak at idle,, also check the cylinder power balance at idle ,and injectors p widht, his is the injectors should stay open,

also where is failing HC CO CO2 OR NOX GIVE ALL THE NUMBERS AT IDLE AND HIGH GOOD LUCK

You can get a additive that you put in your fuel tank. Better when fuel is low. Then give the car a good run and open it up a bit in the gears pref on a motorway. Becuse If you are a person that just plods around town in the traffic and never sees a motorway. Then could be the catalytic Converter on your exhaust system could be blocked. This will defainately affect your Co Readings and can fail the emissions test. The additive is a lot cheaper than the Cat. Worth a try if you can only sees town traffic. Failing that if the MOT man is a nice man asdk him to stick a rag in the exhaust with the emission pipe and that normally works too. I doubt he would though. Worth an ask.