Fiesta Zetec S Emissions Fault

[sazshx]

Hello guys, I've got a 2000 Ford Fiesta Zetec S 1.6 (silver top engine), this is burning oil and has failed emissions for CO and Hydrocarbons, curiously it has passed for lambda emissions.

My current theory is the burnt oil has fouled o2 sensors, what I don't understand though is if why, if this is the case, has lambda sensor been unaffected? What do you guys think, has anyone got experience with these engines, would burning oil fail emissions or is this only the case if its also running rich? TIA

[TwinKam]

'Lambda', in emissions terms, is just a theoretical number calculated from all the measured gases, fiddled so that ideally the result = 1.0 Hence 'lambda' does not have its own sensor; 'lambda sensor' is a misnomer but is often used in place of 'oxygen sensor', they are one and the same thing, and it's far less confusing to just refer to it as the 'oxygen sensor'.
Simply put, high HC is burnt oil, high CO is unburnt fuel/oil.
Post up the full emissions print-out, it will be interesting to see how it still ended up with the Lambda reading near to 1.0 (0.97 to 1.03)... but ultimately cleaning or even renewing the oxygen sensor isn't going to solve your issue or get you through the MoT.