Codes P0420 and P0430?

Hello Joe,

Thank you for the prompt response.

Minor correction here, upon plugging in my OBD just now it turned out that the code is P0430, which is in fact the same exact code that had first turned up prior to swapping my bank 2 cat.

If that means anything, it would most probably indicate that the issue had not been the cat to begin with because I have changed that with an original OEM ford part.

I'm leaning towards a faulty upstream bank 2 O2 sensor, since I have already replaced both downstream sensors (B2 + B1) and bank 2 Cat. This leads me to the conclusion that there is nothing left to be swapped out except for my upstream B2 sensor.

Going to get it replaced tonight, and matter of fact I will not be clearing the codes this time as I want to see if the PCM is going to recalibrate itself with the new readings and clear the code by itself which will be solid proof in determining the source of this issue.

And it is a 3.5 V6 Taurus with no other cords except for the 430 as for the odor, nothing worrying to be frank except for when I WOT. Funny smell not rotten eggs or anything of that sort. More like a burning clutch but I would actually blame that on the aged hoses and pipes in the engine bay.

Hello Joe,

it turned out to be faulty spark plugs and ignition coils. The guy whom I've bought the vehicle from had installed aftermarket ignition coils which had led to a rich AFR mix (always wondered why it had done that. Got me thinking something was off in my exhaust valves).
Had a whole set replaced and I haven't had the code appear since my last reset -yesterday- (which usually used to pop back up in a matter of hours if not minutes).

Spoke too soon, lol.
It just popped back on, my mechanic had previously said; one, if not a couple of the exhaust valves are not shutting off properly due to a failing sealant with the camshaft.

I had not wanted to believe what he said, but post having replaced absolutely everything within the engine block (spark plugs-injection coils-fuel injectors-fuel pump-cats-o2 sensors) I'm left with no option but settle with what he said.

His resolution is to either live with it and drive as gently as possible for a bit of time till little carbon builds up around the valves and they are finally in situ (as in prior to me adding some 4 bottles of fuel system cleaners over a 2 months period) OR crack open the engine head and fixing the loose valve.

Having had spent close to 2200 USD in an attempt to get this sorted out, I think I'm going to go with the first option.

Hey Joe,

He basically said the valves are not shutting off properly when they are supposed to.
With the buildup of a small layer of carbon (bound to happen anyways) to fill the voids where the valves are not shutting off properly the CEL is not going to show up no more.
I just need to drive moderately and not slam the throttle. Let me know what you think.

Hey Joe,

I'll be on top of that. I have seen a buddy of mine perform that test using a computer.

Moreover, aren't the cylinders supposed to misfire if there is an exhaust/intake valves leak? Or does it need to develop into a considerable leak in order to cause a misfire?

Hey Joe,

I have had conducted a digital (computer based) cylinder compression which showed all values to be okay except for cylinder 5 which had showed 1% deviation and that's when I resorted to the basic mechanical compression test (you recommended), and it turned out cylinder 5 was doing just fine and no leak is present.

It came to my attention that my LTFTs are always -8% whenever the CEL shows up. It feels like my mixture is rich although I've cleaned my MAF sensor and throttle and air filter - replaced sparks plugs + ignition coils + injectors.

I'm highly leaning towards deleting the cats and disabling my down-streams, but this might be a cause for high carbon smell in the cabin along with a risk of not passing my annual vehicle registration test.

Worth mentioning that the vehicle is not exhibiting any misfires or rough idles.

Just to add, LTFT are -8.6% on idle and tends to fluctuate between -8 and 0 % upon accelerating (bank 2)
Whilst bank 1 is -6% at idle and fluctuates the same as the above.