avfcboy1974

Hi all, I had the eml come on and when obtaining the dtc code it came back as p0420 which is something to do with the catalytic converter. Ive erased the code and not noticed any difference in performance and the eml has not came back on nor has the code came back after driving roughly a further 80 miles. Do I need to do anything or just leave it ? Thank you

Cossie Sean

Cat Efficiancy below threshold usually,

might be a poor batch of fuel, try it for a week and see if it returns, nothing drastic.

few good spankings to get the cat nice and hot

avfcboy1974

Thanks Cossie ill give that a go

GVK.

It will come back on, at some point...normally does..

Usually Fords get this code if they have had a misfire due to failed coil pack or whatever,with excess unburnt fuel going into the cat.. then after the misfire is fixed the next thing that can happen is the EML light comes on with the P0420.

Ideally needs the pre & post cat lambda sensor live data checking in graph form to see if the pre & post lambda signals are the same. If the cat is fooked, both the signals will be the same, if the cat is good, you'll just get a constant voltage on the post cat lambda while the pre-cat lambda is switching once in closed loop operation.