159 2.4 20007 plate
19,500 DPF/EGR by
AO Silver Member
Join Date: May 2009
Location: United Kingdom
What were the emissions it failed on?
CO or hydrocarbons? Is the engine light on?
It could be anything from relatively cheap including leaking exhaust, lambda sensor, MAP sensor, failed CAT, leaking injector, blocked air filter, just needing a good service to much more expensive like worn rings or head gasket starting to fail.
Tell us what all the readings were both high and low rpm and what service history there is and we can direct you more clearly.
Lambda is a reasonable call but the reading will help.