Code P0420

Tiny
WROJAS0919
  • MEMBER
  • 2003 MITSUBISHI LANCER
  • 124,600 MILES
Need help please. Don't know if it's the downstream sensor ar catalystic. Thanks
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Friday, March 4th, 2016 AT 10:39 AM

8 Replies

Tiny
DRCRANKNWRENCH
  • MEMBER
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.
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Friday, March 4th, 2016 AT 11:18 AM
Tiny
WRENCHER1
  • EXPERT
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%
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Friday, March 4th, 2016 AT 3:21 PM
Tiny
WROJAS0919
  • MEMBER
Thanks for the reply!
How would I be able to tell if its a leak?
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Friday, March 4th, 2016 AT 3:35 PM
Tiny
WRENCHER1
  • EXPERT
You put it up on a lift with the engine running and carefully feel all around until you feel the air puffing.
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Friday, March 4th, 2016 AT 3:58 PM
Tiny
WROJAS0919
  • MEMBER
Its not a leak, the car has two catalystics how can I tell witch one it is? And it only has two sensor :/.
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Friday, July 29th, 2016 AT 3:45 PM
Tiny
WRENCHER1
  • EXPERT
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.
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Friday, July 29th, 2016 AT 4:03 PM
Tiny
WROJAS0919
  • MEMBER
Thansk for your answer, so then I shouldnt think its the converter attached to the manifold?
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Friday, July 29th, 2016 AT 6:19 PM
Tiny
WRENCHER1
  • EXPERT
The one between the 2 sensors is the one being monitored.
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Friday, July 29th, 2016 AT 6:21 PM

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