P0420 on a 2001 Pontiac Bonneville, diagnostic and correction - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


2000-2005 Discuss your 2000-2005 Bonneville SE, SLE, and SSEi Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 04-30-2011, 12:52 PM   #1
Retired Administrator

True Car Nut
Thread Starter
 
GunsOfNavarone's Avatar
 
Join Date: Apr 2009
Location: Williamsport, PA
Posts: 2,856
Thanked 167 Times in 129 Posts
GunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud of
Default P0420 on a 2001 Pontiac Bonneville, diagnostic and correction

P0420 on a 2001 Pontiac Bonneville, diagnostic and correction:

Just spent a month and a ton of fuel trying to diagnose and correct a P0420 error so I could pass the emissions test, the SES light was lit.

First I cleared the error, and did a visual inspection of the oxygen sensors, catalytic converter and exhaust system. Everything looked ok. After driving about 40 miles, the P0420 came on again. Did a mega seafoam treatment, reset OBD and 40 miles later, SES and P0420 came on again.

Replaced the oxygen sensors with new Delphi sensors, and the P0420 came on after 80 miles. Tried all kinds of combinations, but nothing worked except my wallet buying fuel, driving around to see if code returned.

Purchased and replaced the catalytic converter. That corrected the P0420 issue, but now I could not get 5 of the 6 required OBDII ready states for emissions testing. I tried driving a few hundred miles, but only 4 of the 6 ready came up. Did some research and discovered the drive cycle to get the ready conditions set.

What I discovered after two weeks was there are two GM drive cycles and that the 2001 Bonneville only likes one of them. The main issue was to get the heated oxygen sensor to ready. What is published most often to get the heated oxygen sensor to cycle to ready is t start engine when cold, and let it idle for 3 minutes with a/c and rear defrost on. This does not work for the Bonny. What is required for the Bonny is to start engine when cold, and immediately put car into drive (with foot on brake) for three minutes.

I tested the above a few times and the results stayed the same. I am able to get 5 of the 6 Bonny tests to ready mode in under ten minutes if starting from a cold engine, which is better than driving hundreds of miles and hoping the tests cycle. The right test cycle procedure was the critical factor.
GunsOfNavarone is offline   Reply With Quote
Old 04-30-2011, 12:58 PM   #2
Senior Member
Certified GM nut
 
SignOfZeta's Avatar
 
Join Date: Mar 2005
Location: New Milford, CT
Posts: 2,284
Thanked 16 Times in 13 Posts
SignOfZeta has a spectacular aura aboutSignOfZeta has a spectacular aura about
Default

Have you tried the steps in How to set readiness of emissions?
SignOfZeta is offline   Reply With Quote
Old 04-30-2011, 01:12 PM   #3
Retired Administrator

True Car Nut
Thread Starter
 
GunsOfNavarone's Avatar
 
Join Date: Apr 2009
Location: Williamsport, PA
Posts: 2,856
Thanked 167 Times in 129 Posts
GunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud of
Default

Yes I did, and discovered on my 2001 SSEi that the below step doesn't trigger the ready.


2. Idle the engine in drive for 2 1/2 minutes with the air conditioner and rear defroster on. You want a lot of electrical load. The more the better. This will run diagnostic tests for O2 heater, Purge "No Flow", Misfire, Passive Air, Fuel Trim and if closed loop is achieved.

What triggers the ready is to start and put into drive immediately (with foot on brake) for 3 minutes. The difference maker was to idle the Bonny in gear, not in park, I did not run have to run the a/c or the rear defrost.
GunsOfNavarone is offline   Reply With Quote
Old 04-30-2011, 01:30 PM   #4
Retired Senior Admin

Expert Gearhead
 
Danthurs's Avatar
 
Join Date: May 2006
Location: Sheboygan Wisconsin
Posts: 29,661
Thanks: 0
Thanked 16 Times in 13 Posts
Danthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to all
Default

Sad thing is you could have drove up here, paid for a tune and I could have fixed you right up.
Danthurs is offline   Reply With Quote
Old 04-30-2011, 01:48 PM   #5
Retired Administrator

True Car Nut
Thread Starter
 
GunsOfNavarone's Avatar
 
Join Date: Apr 2009
Location: Williamsport, PA
Posts: 2,856
Thanked 167 Times in 129 Posts
GunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud ofGunsOfNavarone has much to be proud of
Default

Dan,

You are right and after all time and money- I would of done that looking back.....
GunsOfNavarone is offline   Reply With Quote
Old 04-30-2011, 01:57 PM   #6
Retired Senior Admin

Expert Gearhead
 
Danthurs's Avatar
 
Join Date: May 2006
Location: Sheboygan Wisconsin
Posts: 29,661
Thanks: 0
Thanked 16 Times in 13 Posts
Danthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to all
Default

Hind sight is 20/20
Danthurs is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
2000 Bonneville - My AC Quit On Me :( - Need Proper Diagnostic Procedure - Help! GM-Ryder 2000-2005 6 07-16-2015 11:01 AM
1998 Random cylinder misfires and code P0420 jllracer55 1992-1999 0 10-07-2008 12:41 PM
Great, another SES Light, P0420 jseklund 2000-2005 3 04-06-2006 07:50 PM
P0420 Catalyst System Low Efficiency marksssei 1992-1999 5 11-28-2005 01:23 PM
2001 bonneville 2001 grand prix engine Boombata Performance, Brainstorming & Tuning 10 10-10-2005 04:55 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 10:05 PM.


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.