Hi all,

First of all my car: A 2015 Ford Focus 1.0L Ecoboost Mk3. Some time ago (a few months now) the engine management lamp came on, I read the code with Forscan and it was P0420. I cleared the code but after a while it came back, again, and again and again. and this occurs every 30-40 miles or so (ish)

The P0420 code was: Catalyst below threshold - Bank 1.

Now other things that I have done since are: Changed the spark plugs and Changed the coil packs but still the P0420 kept showing up. I then changed both upstream and downstream oxygen sensors, but same issue keeps coming up. Hmmm, so thinking perhaps it is the cat itself that might be knackered, I then placed an O2 sensor spacer between the cat and the downstream oxygen sensor, but, yep, you guessed it - same P0420 came up this morning.

Has anybody come across this sort of thing before and might be able to point me in the right direction?

thanks.

4 hours ago, leohopkins said:

Hmmm, so thinking perhaps it is the cat itself that might be knackered,

👍