Nissan Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
I have a 2008 Altima and the service engine soon light come on and the diagnostic tool says code PO420 is showing and its probably the CatConv. Does anyone know if I should change the 02 sensors first, new gas cap, add fuel additive to help clean CC, change the CC, which is the most expensive step. I'm just looking for someone who has encountered this problem and who have some valuable information to help me save money and time in diagnosing this issue. Car seems to be running fine but something minor is starting to happen to cause a code to pop up. Thanks for any information you may have to help me in this issue.
 

·
Nissan Enthusiast
Joined
·
3,046 Posts

Its been written about many a time. Is it impossible for people to do searches here? If you are going to be replacing the cat manifold, you would be having to replace the o2 sensors anyway. I would try starting with the upstream one.
 

·
Sup Mod keeping the peace
Joined
·
6,359 Posts
I have a 2008 Altima and the service engine soon light come on and the diagnostic tool says code PO420 is showing and its probably the CatConv. Does anyone know if I should change the 02 sensors first, new gas cap, add fuel additive to help clean CC, change the CC, which is the most expensive step. I'm just looking for someone who has encountered this problem and who have some valuable information to help me save money and time in diagnosing this issue. Car seems to be running fine but something minor is starting to happen to cause a code to pop up. Thanks for any information you may have to help me in this issue.
The P0420 fault code is triggered by the catalyst system efficiency being below threshold. Here are some of the possible causes:

  • - The three way catalyst (manifold) is mechanically defective or poisoned.
  • - Exhaust pipe may have a leak.
  • - Intake system air leaks.
  • - One or more fuel injector defective.
  • - Fuel injector leaks
  • - Dirty spark plug(s).
 

·
Registered
Joined
·
11 Posts
If everything else checked out OK with the car if it were me I'd change the 02 sensor before going head first with a catalytic converter.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #5
The P0420 fault code is triggered by the catalyst system efficiency being below threshold. Here are some of the possible causes:

  • - The three way catalyst (manifold) is mechanically defective or poisoned.
  • - Exhaust pipe may have a leak.
  • - Intake system air leaks.
  • - One or more fuel injector defective.
  • - Fuel injector leaks
  • - Dirty spark plug(s).

I have changed both Catalytic Converters and replaced the tmps that were causing low tire light to stay on for sometime now and all lights went out and then two days later the Service engine light came on again. We'll get there eventually!
 
1 - 7 of 7 Posts
Top