Hi,

51 plate focus failed emissions test on Hydrocarbons and co2. what could be causing this and how could i fix it?

cheers

Your engine has carboned up through general use and your cat is probably filthy.

Two options- new cat or a terraclean.

Search the web for terraclean challenge to see if you have a garage nearby that provides this service.

You may find it costs up to £100 but you'll definitely pass your emissions after.

if you could post up all the figures including CO, might help to work out whats happening.

HC = unburnt fuel going straight into exhaust

CO2 = air/fuel mixture

as an example

if your CO reading is low, HC and CO2 are high.

then that would indicate that oxygen sensors are detecting unregulated air, which in turn increases fueling to compensate...or simplified, an air leak

would need all 3 figures to give a clue to what is happening.

Just checked and they did not leave the figures with the paperwork

I did take ht leads of and in the chambers it was full of oil. Coupke of months ago i left the oil cap off so presume it filled then cleaned it and its running better now. Do u think that would have skewed emmissions?

tough to answer without those figures

low CO [pass test]

high HC [fail]

low CO2 [fail]

would indicate a misfire, which could occur with oil in plug recesses

just read the paperwork again, and it was CO which was high not the CO2

So High CO and HC.

Car is running better now I have cleared the oil from the spark plug chambers and no new oil has appeared so I am hoping it was just that. Will blast it before MOT to see if that helps.

Could I check anything else?

that indicates a rich mixture....number of possibles

again, figures would help.

temp sensor/oxygen sensor/map sensor/air leaks/injector leak/fuel pressure etc etc

if it was me and i didnt have anyway of checking figures before taking back.

new oil/filter, plugs, air filter, either a new fuel filter or remove and drain, then refill with a cleaner, then take for a good italian tune up just before trying to put through again

update for you.

cleared the oil out of the spark plug chamber and 'italian tuned' the car - retested and passed the emmission flying colours

cool