Code P0420

WROJAS0919

MEMBER
2003 MITSUBISHI LANCER
124,600 MILES

Need help please. Don't know if it's the downstream sensor ar catalystic. Thanks

Friday, March 4th, 2016 AT 10:39 AM

8 Replies

DRCRANKNWRENCH

MECHANIC
3,380 POSTS

I looked up the code in our online guide. Attached are the notes from said code. Let me know if you need more information. One of the sensors probably needs replacement.

Images (Click to make bigger)

SPONSORED LINKS

Was this

answer

helpful?

Yes

Friday, March 4th, 2016 AT 11:18 AM

WRENCHTECH

MECHANIC
20,761 POSTS

I've seen this code a lot and there are just 2 things that i've ever seen set it

Bad converter 95%
Exhaust leak ahead of the converter 5%

Was this

answer

helpful?

Yes

Friday, March 4th, 2016 AT 3:21 PM

WROJAS0919

MEMBER
13 POSTS

Thanks for the reply!
How would I be able to tell if its a leak?

Was this

answer

helpful?

Yes

Friday, March 4th, 2016 AT 3:35 PM

WRENCHTECH

MECHANIC
20,761 POSTS

You put it up on a lift with the engine running and carefully feel all around until you feel the air puffing.

Was this

answer

helpful?

Yes

Friday, March 4th, 2016 AT 3:58 PM

WROJAS0919

MEMBER
13 POSTS

Its not a leak, the car has two catalystics how can I tell witch one it is? And it only has two sensor :/.

SPONSORED LINKS

Was this

answer

helpful?

Yes

Friday, July 29th, 2016 AT 3:45 PM

WRENCHTECH

MECHANIC
20,761 POSTS

P0420 applies to bank one if you have a V6. That is the only bank if you have a 4 cylinder. It will be the converter just ahead of the downstream sensor. The sensor could be right in the converter itself.

Was this

answer

helpful?

Yes

Friday, July 29th, 2016 AT 4:03 PM

WROJAS0919