Hello folks! New here because I bought a 2009 Fit Sport. Thought I was making a good decision…..but it turns out maybe not so good.

The car was purchased from the original owner who was a maintenance freak….literally pages of records…and it shows. The car has just over 300,000 miles! Runs and drives beautifully. Since we won’t put many miles/year on it, I figured it would still outlast us.
Unfortunately, the CEL came on yesterday…after only 100 miles since purchasing it. The dreaded Code P0420.

Soooo….i am in need of advice from people more knowledgeable and experienced.

Some key info…by his records:
The O2 sensors (both pre and post-Cat) were replaced and throttle body cleaned at 239700. Don’t know if OEM.
All 4 ignition coils and plugs were replaced at 246800. Don’t know if OEM.
Oil/filter changes at roughly 5000 mile intervals with Mobile 1 full synthetic and Bosch premium filters
Trans fluid (DW1) changed at recommended intervals
Coolant changed at recommended intervals
Air filter changed at recommended intervals

Well….you get the idea. Well maintained.

Here’s my problem….the car runs and drives beautifully !!!

Should I: 1) just ignore CEL and drive it until it has issues
2) attempt to use a method (or several) to ‘clean’ the catalytic converter
​​​​​​ 3) spend HUGE money on replacing Cat with OEM
4) spend less (but still huge) on good aftermarket Cat

Remember….we will not be putting lots of miles on it, but really would like it to be reasonably reliable and hopefully last a few years. I was inspired by reading threads here about amazingly high mileage so thought it would be no problem…..but apparently not so lucky. Should have realized that catalytic converter longevity is limited despite excellent maintenance.

Any and all advice will be greatly appreciated. Thanks.

 

Sorry….forgot to note an important detail…..car does NOT have to pass inspection here.

 

I think you should get the fault codes out of the system to make wise decisions.

 

Not sure if this is good help or not but I have gotten around many P0420s by throwing on an O2 spacer. I know some are more sensitive than others. Some you have to drill out the hole more to allow a specific amount of air flow. My Subaru I have had to do that on and then get codes saying the O2 is not getting enough exhaust in it.

Worth trying. Just throwing the idea out there for you.

 

What he said ^^.

I would start by this 10-20$ mod first.

 

Thanks for the replies. As noted in first post, the fault code was P0420. There were no other codes. I have seen examples of ‘spacing’ the downstream O2 sensor to reduce sensitivity and avoid the code. Certainly might be handy to pass an emissions test.
However, since testing is not an issue for me, I guess what I’m really trying to determine is whether continuing to drive a great running high mileage car with a P0420 code will actually hurt anything. Obviously there are several causes for this code other than a bad converter…and bear investigation . However, assuming converter is truly bad, presumably if the catalytic converter is simply ‘used up’ (it does have over 300000 mi) rather than obstructed by carbon due to a tuning issue, there should be no increased back pressure. So what’s the worry??? Thoughts???

 

Sorry, I just somehow managed to miss the code in your first post. I would drive it awhile with heavy foot, maybe two tanks or so, then clear code and see if it repeats. If it does then I could try the recommended spacer.

 

It's not super practical to drive a car with a pendant code as it'll mask any other code, which might be important.

Worst case if you are unsure, install a high flow cat with a spacer for the O2 sensor and be done with it. Will probably be under 200$...

 

Dude, you’ve got a bad Cat. I’d replace it and feel good about yourself and the environment. Used/reman.

 

The 20-Minute Japanese Trick to Unclog a Catalytic Converter

Try this before you replace the cat.

 

Got a time stamp to cut through the heavy filler BS?