Last week, I got an engine warning light but didn’t notice any change in how the car runs. I bought an OBD scanner and found it was throwing a P0420 code.
Called my mechanic, and before I could explain further, he asked where I last fueled up. I usually go to my regular Texaco station, but this time I used fuel from Asda. He told me not to use their fuel, suggested running the car down to 5-10 miles left in the tank, adding a petrol cleaner, and refilling it completely.
Has anyone else had this happen? Any other advice? For reference, it’s a 16-plate 1.0 Ecoboost.
I had a similar issue earlier this year after filling up at Sainsbury’s. Got a P0420 code but cleared it and switched to running only V-Power fuel. The code hasn’t come back since (touch wood).
I’m skeptical of this advice. The P0420 code usually comes up when the downstream O2 sensor detects lean/rich cycling because the catalytic converter isn’t absorbing these fluctuations anymore. Normally, this means you need to replace the cat. I’ve never heard of a fuel cleaner fixing this issue.
@Willoughby
I had a similar issue after filling up at a smaller, cheaper gas station and driving super cautiously. Switching to a better fuel station and altering my driving style (shifting gears at 3,000 RPM instead of 2,000 RPM) helped a lot.
Focuses seem to be really picky about everything. I’ve had cars where I could use cheap spark plugs and fuel from anywhere, but not with this one. Stick to Motorcraft plugs and premium fuel (I use 98 octane in Poland). Even small changes like these made a big difference, and the P0420 code stopped showing up.
I have the same code. Took it to the dealership where I work, and the tech said my catalytic converter is failing. I’m not driving it much now and using my other car instead. Hopefully, yours isn’t as serious and is something easier to fix. Mine’s a 2014 SE.