I've had just P0420 a couple of times already. but now I have that AND P0430. O2 sensors are little more than a year old. New converter or could it just be dirty and need some cleaning? Could it also possibly be causing the weird quirks I have going on with the car right now?

 

I don't see a p0430 listed for a 98 4-cylinder accord.

 

It came up on the scan tool. Definitely P0420, and the P0430 showed up underneath of that. But yeah, I can see your point as it's not the 3.0L. Weird.

But either way, does this meant cat replacement or is it just kinda plugged up? I smacked my palm against it a couple of times and it didn't rattle.

 

What other weird quirks are happening with your car?

 

If you have a scanner that can display graphed O2 sensor performance, then monitor the sensor 2 (aft of converter) data. If the voltage trace oscillates from High (0.7-0.9 V) to low (0.1-0.3V), then converter is likely failed. A steady, slowly changing voltage is sign of intact converter.


good luck

 

The pulsing RPMs while cold (https://www.hondaaccordforum.com/for...ms-gear-62869/) and the mystery vibration (https://www.hondaaccordforum.com/for...bration-62854/).

I'll swing back by O'Reilly in the next day or two and see if they can run the data on one of their scanners.

If indeed the cat is toast, how do I know which one to get?

 

Went to O'Reilly and used their scan tool, and the real time voltage signal was bouncing from about 0.1-0.8V every couple of seconds. I guess it's probably safe to say that the cat has gone the way of all the earth. So now, how do I know which one to replace it with?

 

Were you looking at Bank 1, Sensor 2? If yes, then converter is likely failed. Exhaust leaks can sometimes cause a false P0420 code. Make sure no exhaust leaks.




good luck

 

If this was my vehicle, I'd probably invest in some type of scanner. The P0430 code bothers me, because a bad pcm could give you a false code.

I bought a blue-tooth obd2 adapter and bough torquepro to monitor my sensors (total of around ~$35 invested). You really should verify the upstream air/fuel sensor is responding to the engine exhaust and see what kind of fuel trims you have.

I'd hate to suggest spending money on a new converter and not have it solve the problem.

 

Yes, I hate to jump to a cat replacement but there has been some issues that might have helped it go....I think there was a HG failure, then a leaking intake gasket and maybe another one or two.

"BLACKLX" - If you are outside of the country of CA there are plenty of places you can find a replacement cat for decent prices (rock auto, local parts store with discount codes, ect). "IF" you go down that road, go ahead and get new O2's (up and down stream) and replace those as well, if they are more than ~a year old. Then look online for a "used cat buyer" - the metals used in them will get you some money back.....say $50 to $100.

Again I hope I'm wrong and the cat is not the issue but if it is I'm just giving some ideas.