SaturnFans.com
what's new (beta) - classifieds - forums - photos


Go Back   SaturnFans.com Forums > Models > Saturn S-Series > S-Series Tech
Register FAQ Members List Groups Calendar Chat Room Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
Old 11-08-2011, 06:24 PM   #1
brianolda
Junior Member
brianolda is on a distinguished road
 
Join Date: Mar 2011
Posts: 10
Default code P0420 Need help

this code means catalyst system efficiency below thresh hold. Does any one know what this means????

REWARD EXCELLENCE!

Add to brianolda's Reputation
Rate the quality of this post and help brianolda reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
brianolda is offline   Reply With Quote
SaturnFans.com Sponsored Links
Old 11-08-2011, 06:31 PM   #2
BV22
Master Member
BV22 is a glorious beacon of lightBV22 is a glorious beacon of lightBV22 is a glorious beacon of lightBV22 is a glorious beacon of lightBV22 is a glorious beacon of lightBV22 is a glorious beacon of light
 
Join Date: Feb 2011
Location: Texas
Posts: 2,151

2002 SC1
Default Re: code P0420 Need help

It usually means the catalytic converter has reached the end of its useful life and must be replaced to pass emissions. Occasionally, a failing rear O2 sensor can give this code. Year, model, mileage and oil consumption rate of your car would help.

...
BV22
2002 SC1 5M
RIP Sept 1 2018
315,344 miles

REWARD EXCELLENCE!

Add to BV22's Reputation
Rate the quality of this post and help BV22 reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
BV22 is offline   Reply With Quote
Old 11-08-2011, 06:46 PM   #3
brianolda
Junior Member
brianolda is on a distinguished road
 
Join Date: Mar 2011
Posts: 10
Default Re: code P0420 Need help

Yes I bet it would. 1998 SL1 SOHC Frsh rebuild on the motor. Thanks for the help

REWARD EXCELLENCE!

Add to brianolda's Reputation
Rate the quality of this post and help brianolda reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
brianolda is offline   Reply With Quote
Old 11-08-2011, 07:27 PM   #4
madpogue
Super Member
madpogue has much to be proud ofmadpogue has much to be proud ofmadpogue has much to be proud ofmadpogue has much to be proud ofmadpogue has much to be proud ofmadpogue has much to be proud ofmadpogue has much to be proud ofmadpogue has much to be proud of
 
Join Date: Sep 2004
Location: Madison, WI USA
Posts: 25,715
 

1996 SW2
Default Re: code P0420 Need help

A 420 can throw from something as simple as an exhaust leak upstream of the rear O2 sensor. Check the manifold/downpipe joint (uh-oh, I wrote "420" and "joint" in the same post....), around the flex-pipe, and the inlet to the cat. If the rebuild was recent, the manifold/downpipe connection may be a bit loose. Doesn't take much; I had ONE of the three downpipe flange nuts loose, maybe 1/4 turn, and that was enough to throw a 420.

REWARD EXCELLENCE!

Add to madpogue's Reputation
Rate the quality of this post and help madpogue reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
madpogue is offline   Reply With Quote
Old 11-08-2011, 07:30 PM   #5
OldNuc
Super Member
OldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond repute
 
Join Date: Apr 2008
Location: Far Southwestern Iowa
Posts: 66,683
 

1998 SC2
Default Re: code P0420 Need help

Pull the PCM B fuse(UHJB) and then replace it. Go for a drive and see if the 420 comes back. The 420 may be the result of the rebuilding or it also can be caused by any exhaust leak between the head and CAT inlet. Hold a towel on the exhaust and feel for leaks, a very small one is all that is required to do this.

REWARD EXCELLENCE!

Add to OldNuc's Reputation
Rate the quality of this post and help OldNuc reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
OldNuc is offline   Reply With Quote
Old 11-09-2011, 12:24 AM   #6
td1238
Master Member
td1238 will become famous soon enoughtd1238 will become famous soon enough
 
Join Date: Mar 2010
Location: Milwaukee
Posts: 2,108

1999 SL2
Default Re: code P0420 Need help

A P0420 can also be caused by a cat converter that's being heavily taxed, but isn't necessarily at the end of its useful life.

On one friend's car it was a weak ignition coil that was causing a misfire on one cylinder. This both sends unused fuel and unused oxygen into the exhaust. Replacing the ignition coil eliminated the misfire, and within moments the P0420 code also went away, and has been gone for over a year now.

On my '99 SL2 it was weak ignition coils, a burned exhaust valve, imbalanced injectors, and moderately heavy oil burning. At 219,000 miles of this abuse I was able to partially revive the cat, but in the end I wound up replacing it.

On another friend's car it was a faulty upstream oxygen sensor that was causing the engine to run too rich. Replacing the oxygen sensor made the engine run far better, and has caused the P0420 code to go away for months now.

In the cases where the code went away, the cat was taxed, but not enough to destroy it. Fixing the problem in a timely manner saved the cat.

Oil burning can clog the cat, and long-term oil burning can destroy it.

See to it that your ignition coils are in good condition (measure over 8k ohms at room temperature), and that the ignition system in general is well maintained, that your injectors are clean, oxygen sensors are functioning properly, all other sensors (temp, TPS, MAP, etc.) are functioning properly, that there are no exhaust leaks, especially before the cat, and that the engine doesn't burn excessive amounts of oil and absolutely no antifreeze (just in case). Then, if the P0420 code won't go away, you likely will have to replace the catalytic converter. Absolutely do not replace the converter until you are sure that all other faults are eliminated from the engine, and only after you cannot get the code to stay off.

REWARD EXCELLENCE!

Add to td1238's Reputation
Rate the quality of this post and help td1238 reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
td1238 is offline   Reply With Quote
Old 11-10-2011, 12:39 AM   #7
td1238
Master Member
td1238 will become famous soon enoughtd1238 will become famous soon enough
 
Join Date: Mar 2010
Location: Milwaukee
Posts: 2,108

1999 SL2
Default Re: code P0420 Need help

Another common cause for a misfire (which can cause a P0420 code) is oil on the spark plugs and boots. I didn't think of this until I read another post, but on cars where the spark plug passes through the valve area, oil leaks are common here. If there is a lot of oil around the plug, it can cause it to misfire, especially when under load, which can tax the cat and throw a code.

Consider all possibilities mentioned. ...And again, absolutely do not replace the cat until all engine performance issues (including excessive oil burning) are corrected, or until the code cannot be cleared (sometimes, once the engine problem is corrected, the cat resumes normal performance, and the code disappears). If the problem(s) is not corrected, it will only ruin a new cat.

REWARD EXCELLENCE!

Add to td1238's Reputation
Rate the quality of this post and help td1238 reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
td1238 is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
P0420 Code ezzieyguywuf S-Series Tech 33 05-03-2011 05:33 PM
code P0420 Frankd1 S-Series Tech 9 11-14-2009 10:13 AM
help i got a code that is P0420 butters122706 L-Series Tech 0 06-13-2009 11:00 AM
Another P0420 code alleninpa S-Series General 7 09-02-2007 03:03 AM
P0420 Code angelaw S-Series General 9 11-22-2006 09:47 AM


All times are GMT -4. The time now is 04:26 PM.

Advanced Forum Search | Advanced Photo Search


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
SaturnFans.com. The Saturn Enthusiasts Site.