Emissions Failure

[Timmyirl]

Hi, I have a Citroen c5 2002 1749cc petrol, I have put her through the nct (mot) and it has failed on emissions twice! Here are the readings

Low idle 720rpm Co 0.47 vol% hc 190ppm

High idle lambda : 1.02, 2910rpm, CO 0.56 vol%, HC 119ppm! Any help is appreciated?

[paul.h]

Welcome to the forum.

 

It looks to be running a bit rich since the CO values are above the limits. You could give the car a service - new air filter, spark plugs, possibly oil/filter change, clean the throttle body and also give the car a good run so it is warmed up before the MOT. Also check for any air leaks between the air filter and engine and any on the exhaust side up to the catalyst.

 

However, ideally you would use a code reader with live data to check the exhaust catalyst inlet and outlet lambda sensors - the inlet should be about 1.0 and constantly switching but the outlet should be a steady value. If the outlet one is switching similar to the inlet then the catalyst needs replacing.