Any word before working on the Cat Converter?

[ihaveaquestion]

Well, I've been getting P0420 for a while now, I always turn it off but it always comes back after a few months. I start thinking I should do something about it...because my engine just isn't running very smoothly. This is after I've changed rotor, spark plugs & wires and air filter. Seafoam helped quite a bit which led me to believe it's the dirt inside that's causing the performance drop.

My car has 170k miles and I've been skipping maintenance here and there ( I know I've committed a crime). Well, the process looks simple enough, unless I miss something, 6 bolts and it's out. But I heard these are some of the toughest bolts to loosen. So is there any tips on doing this? I probably should get a good set of jack stand first.

 

[dv8801]

depends, when i changed my cat, the bolts where rusted so bad i have to cut all bolts off and use new bolts.

 

[RedRyder]

PB Blaster

 

[Bax]

+1 on the Blaster.
Also, have a breaker bar handy.

 

[001Stunna]

You can try something like PB Blaster(as chris mentioned) or other means of penetrating oil but chances are if its been awhile those bolts will be pretty rusted and seized/fused on.

Do you hear any rattling from the cat.converter? Have you checked that its not the o2 sensor that has gone bad?

 

[ihaveaquestion]

I do have a breaker bar ready and plan on using PB blaster. But if all fails, what do I do to get it out? I don't have a torch or fancy tool to cut the bolts...

I probably should seafoam the car again. But that thing has been there for 14 years and never come off, I think it might be time to clean it thoroughly instead of relying on seafoam.

I haven't check the condition of O2 sensor yet, I will do that while working on the cat. converter.

 

[RedRyder]

I wouldn’t touch it until you have “Plan B” tools, or can work at someone’s garage who does. If the bolts are seized…your options are quite limited and you’ll need the right tool for the job (torch, drill, etc). The key to working on parts of the car that may be very old and rusty is being prepared.

Jack it up and get under there and look at the hardware at both ends of the cat, you’ll likely be able to tell how hard/easy of a job it’s gonna be.

 

[Jefe02]

I would check the o2 sensors before you touch the cat. I was getting the same code awhile back and I put in new o2 sensors and the code never came back.

 

[jdmcg3]

impact gun.

 

[TuRtL3]

i had the same problem a few months ago. my cat was bad so i had to replace it.

if you hear rattling noise than you should replace the cat, if not check the O2 sensor, if the O2 sensor is fine than you can take off the cat and see what is clogging inside.

i took off my cat by WD40 the bolts, let it soak for a couple minutes and used my impact gun. you may break the bolts so have some back up bolts. if they do break you can always drill the bolts out.