Hi everyone. I posted in here a few months ago about my coil pack issues. After some good advice, I was able to successfully replace all four coil packs and spark plugs. The 07 Fit is running great now.

It took me a while to get around to it, but when I finally erased the check engine codes, the check engine light popped back on after about 50 miles driven or so.

I read it and it wasn't the same codes as the coil packs (which I was very thankful for) but it was the darn P0420 code.

I was wondering if this is related to the bad coil packs? Could they have caused my O2 sensor to go bad?

I don't want to just start replacing things without knowing the exact cause of the code. What's the easiest way to find out if any o2 sensors are bad?

Thanks for any feedback.

 

Firstly, a P0420 is not an O2 sensor code, it is a Catalytic Converter efficiency code.

It surely is because the misfiring "gummed up" the Cat.

Now, it's possible the code might go away on it's own after a few resets. But here's a guy who has successfully eliminated the code by running lacquer thinner in the gas tank:


It's worth a shot before spending the "big bucks" on a new Cat.

PS, I wouldn't use as much LT as he did, remember the Fit's gas tank is only 10 gallons...

Please view the video carefully, and try it as a last resort. (I've never had to do it)

 

I've had an annoying p0420 code for a year, ..tried cat clean, seafoam, etc...got stuck on road with a #4 cyl misfire, towed back home, replaced all 4 coils & plugs ...NO more eng light,.misfires, fartin, runs like new!
...09 Fit Sport, 358,800k miles,..I'm goin for 400k now!!!😁