2nd Gen S-series (1995-2005) Tech Discuss 2nd generation s-series (1995-2005) general tech topics here.

P0420

  #1  
Old 03-07-2019, 11:01 AM
FUN-V's Avatar
Starting Member
Thread Starter
Join Date: Sep 2014
Location: Reno, Nevada
Posts: 150
FUN-V is on a distinguished road
Default P0420

I keep getting a P0420 - Powertrain Catalyst system efficiency below threshold (bank 1)
I'm pretty sure I have a leak at my flange gasket (manifold to intermediate pipe)
Would this cause this code?

 
  #2  
Old 03-07-2019, 11:37 AM
Super Member
Join Date: Nov 2016
Location: Ontario canada
Posts: 1,459
DonL is on a distinguished road
Default

Not smoking enough doobies ... is it still the original cat?
 
  #3  
Old 03-07-2019, 12:21 PM
FUN-V's Avatar
Starting Member
Thread Starter
Join Date: Sep 2014
Location: Reno, Nevada
Posts: 150
FUN-V is on a distinguished road
Default

I believe it is
 
  #4  
Old 03-07-2019, 12:57 PM
Mike.308's Avatar
Senior Member
Join Date: Nov 2017
Location: Poland
Posts: 724
Mike.308 is on a distinguished road
Default

From the above, I could say the reason for a blown gasket I guess... A clogged cat?

..more seriously, the CAT code is thrown on comparison O2 sensors before/after cat. Not much place for an error... I mean You could try fixing the gasket and clearing the code, but more likely the cat is over.
 
  #5  
Old 03-07-2019, 01:07 PM
FUN-V's Avatar
Starting Member
Thread Starter
Join Date: Sep 2014
Location: Reno, Nevada
Posts: 150
FUN-V is on a distinguished road
Default

Was hoping to avoid the $250 cat.
Well, I'll change the donuts, re-set the code and see if it pops again.

Thanks guys
 
  #6  
Old 03-07-2019, 02:09 PM
Super Member
Join Date: Nov 2016
Location: Ontario canada
Posts: 1,459
DonL is on a distinguished road
Default

You can try gambling with the cheap ones, I lucked out with mine. But christine had a nightmare with hers.
 
  #7  
Old 03-07-2019, 02:34 PM
FUN-V's Avatar
Starting Member
Thread Starter
Join Date: Sep 2014
Location: Reno, Nevada
Posts: 150
FUN-V is on a distinguished road
Default

Originally Posted by DonL View Post
You can try gambling with the cheap ones, I lucked out with mine. But christine had a nightmare with hers.
Well not cheap, I get them at cost
 
  #8  
Old 03-07-2019, 06:03 PM
FUN-V's Avatar
Starting Member
Thread Starter
Join Date: Sep 2014
Location: Reno, Nevada
Posts: 150
FUN-V is on a distinguished road
Default

Originally Posted by Mike.308 View Post
From the above, I could say the reason for a blown gasket I guess... A clogged cat?

..more seriously, the CAT code is thrown on comparison O2 sensors before/after cat. Not much place for an error... I mean You could try fixing the gasket and clearing the code, but more likely the cat is over.
Yeah, on ours the upstream sensor is on the manifold and the downstream is behind the second cat, so it could be the leaky donut gasket.
I replaced the donut and re-set the code, I'll see if it pops the code again, if so then I'll replace the cat
 
  #9  
Old 03-09-2019, 12:06 AM
FUN-V's Avatar
Starting Member
Thread Starter
Join Date: Sep 2014
Location: Reno, Nevada
Posts: 150
FUN-V is on a distinguished road
Default

So I swapped out the donuts and the code popped again.
Ran the smog check and it says that the catalytic converter passed but the evap didn't.
I'm posting pics of the results, any ideas would be nice, I will replace the cat system, both front and rear if I have to, but I would like to know if I can avoid it.




 
  #10  
Old 03-10-2019, 08:12 AM
FUN-V's Avatar
Starting Member
Thread Starter
Join Date: Sep 2014
Location: Reno, Nevada
Posts: 150
FUN-V is on a distinguished road
Default

any ideas?
 

Thread Tools
Search this Thread
Quick Reply: P0420


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.