Getting 0420 code and have a horrible rattle inside the exhaust at the cat converter. Based on my read of other threads on the topic, it's time to replace the cat. My car: 1998 Accord 4 cyl 5 speed, 101k miles. I'm a pretty solid DIYer so I thought I'd take this on myself but have a few questions for the experts willing to lend some advice.

1. Any particular brand I should be looking for in a new cat?
2. While I'm under the car, should I replace the O2 sensor as well?
3. I anticipate that the bolts will be on there pretty solid - any tips for removing them? Should I have back-up bolts in hand?
4. Any general tips?

Thanks much!

 

I moved your post for more attention.

1. Any particular brand I should be looking for in a new cat?
Eastern and MagnFlow have decent reputations. I would do some googling for reviews and feedback.

2. While I'm under the car, should I replace the O2 sensor as well?
Depends on age/mileage. I would replace if it's over 100K miles or 10 yrs, or you don't know it's age.

3. I anticipate that the bolts will be on there pretty solid - any tips for removing them? Should I have back-up bolts in hand?
Depends on severity of corrosion due to road salt. In TX this is not a problem, but up N it's bad so new bolts are indicated. An air impact is handy to break bolts. I always try to clean exposed threads w/ wire bursh on a drill and spray w/ penetrant to help remove. If bolts are really badly rusted you may need to cut w/ hacksaw, grinder, or other means.

4. Any general tips?
You will need to elevate all 4 wheels on jack stands. Make sure you have good firm support points and secure jack stands.

good luck

 

Thanks TexasHonda. I'll take a crack at it after the Christmas holiday and will let you know how it goes. Good excuse to get an impact wrench - lol! I'll follow up and let you know how it goes.

 

I just replaced the cat on my 95 LX. I got a universal fit magnaflow & it seems to be a pretty decent replacement part. I wished I would've removed the cat before buying the replacement however. The OEM cat had an extended flange for the front hanging support bracket to be attached to, the replacement didn't. I was able to rig some strapping, but it's not as secure as I'd like it to be. Put on exhaust hangers in the middle between the cat & the elbow to the muffler & it seems to have increased the noise from vibration.

The bolts were pretty difficult to break free. It took PB blaster & alot of patience. I'd recommend new bolts as well for the front & rear flanges both.

After it's all said & done I think I'd have been better off to just weld straight pipe on & forget about it. Good luck & hope it goes well for you.

 

Replaced the Cat with advice given above everything went smoothly. Used PB Blaster since the bolts were quite rusty. Couldn't have done it without an impact driver. Next mission is to figure out how to take care of Oxy sensor - car is throwing P0135 code. Oddly, I replaced the Oxy sensor on the Cat when I replaced the Cat. Not sure if the code is for a different sensor (if there is one).

Thanks for all the help!

 

P0135 is an electrical fault in the primary (ahead of converter) O2 sensor. It could be ECU, wiring, connector, or O2 sensor element.

Check resistance of heating element at O2 sensor connector. If open or dead short, replace O2 sensor. Normal resistance is about 10-40 ohms.

good luck