2008 EX CEL and P0420 code

[sp579mm]

On my 2008 Civic EX sedan, CEL came on, PO420 code popped up. I'm fairly certain it's the o2 sensor, but do not know WHICH ONE!. I ordered both parts from a Honda distributor. The code states"A/F ratio concern, Air leak near HO2S bank 1, and faulty catalytic converter. I got some Seaform to start with. Just trying to find the brake boaster line, to get that starter, any help with that as well. Car has 177K.

 

[lethal6]

1st: Changed the thread title to reflect your problem. Please use descriptive titles in the future. Most people just scroll by lazy titles.

2nd: DO NOT use seafoam unless you take the sensors out. You will destroy what ever good O2 sensor is left, if there is one.

3rd: P0420 doesn't automatically mean the O2 sensor is bad. That is just one of the possibilities. You need to troubleshoot the system and or the components associated to this code. You have an air leak which is causing a terrible air fuel ratio from the ecu trying to compensate. Sea Foam isn't going to do squat if there is an air leak or you have a bad cat, nor is it going to fix an O2 sensor problem if that is what is going on, it is more than likely going to make it all worse.

 

[sp579mm]

Thanks.

Can this air leak be fixed by me? Or just take it to my mechanic.

I read that O2 sensors go bad after 100k miles. I have 177k. Wouldn't they need to be replaced anyway?

 

[lethal6]

It's possible, but not knowing you, I have no clue what your level of mechanic ablilty is nor do I know exactly where the leak is to determine weather it is a part replacement, a fix requiring welding, etc.

I don't replace stuff unless needed, service maintenance, or I know they will leave me stranded if high miles and known for failure. O2 sensor won't leave a car dead in the water, so I don't replace them until they go. If you want to toss new ones in, that is your call, your money.

Not that it means much as every car and every owner is a different situation, but my civic had 150k on it when it was totaled and the sensors were original and are possibly still going after someone snagged the motor out of the junk yard.