Main IndexAuto Repair Home Search Posts SEARCH
POSTS
Who's Online WHO'S
ONLINE
Log in LOG
IN









1996 Honda Accord P0420 Causes?


  Email This Post



GoatTamer
Novice

Jul 2, 2012, 10:44 AM

Post #1 of 9 (2232 views)
Shortcut
1996 Honda Accord P0420 Causes? Sign In

Hello all, I have a 1996 Honda Accord LX 2.0L with ~293k miles. Since I bought it a year ago, the exhaust has always had a slightly rich smell - but no sulfur eggs smell. A year ago, I had replaced both bank 1 and bank 2 O2 sensors which cleared out two previous CEL codes, and it then passed emissions just fine. I haven't had a CEL until now.

After looking online for possible solutions, I went to an auto parts store to get a reading off the O2 sensors. The bank 1 sensor fluctuated rapidly from .05-.70, and bank 2 was more stable from .70-.76.

The only other thing I've noticed is that if I turn the A/C on while idling, the idle gets rougher, occasionally dropping from near 700RPMs idling to 300, and sometimes gets into a cycle of dropping to 300, then revving to 700, then repeating.

The most common solution seems to be replacing the catalytic converter. But, I've also read that they rarely fail on their own, and that there's usually something wrong pre-cat that made it clog up. I've been told to buy OEM for durability, but I need to know what I can do to make sure the new cat doesn't get clogged up 6 months from now.


Discretesignals
Veteran / Moderator
Discretesignals profile image

Jul 2, 2012, 11:22 AM

Post #2 of 9 (2217 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In

What were the previous trouble codes?

Need to monitor long and short term fuel trims at different engine operating conditions. The rotten egg smell is an indication that the catalyst is working. You can't tell the rich and lean trend by watching O2 voltages unless you graph them out over a long period of time or unless they hang at a certain voltage range for too long (low switching).

When the idle is surging with the ac on what is the compressor clutch doing? Does it only surge when the ac is on?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


GoatTamer
Novice

Jul 2, 2012, 12:02 PM

Post #3 of 9 (2203 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In

I can't find my personal records in diagnosing the first problem, but I know one was P0141 and I believe with 95% certainty the other was P0135 - they were both circuit malfunctions.

I wouldn't know how to identify what the compressor clutch is doing, but the idle only surges when the A/C is on, otherwise perfectly normal.

If these don't help at all,
  1. What would you suggest as the most cost-efficient solution if emissions are coming up in a month?
  2. Would a local parts store monitor these trims or voltages for free using the same diagnostic tool?
  3. Can I pay a mechanic to diagnose the problem and then attempt to fix it myself?
  4. It looks like swapping out a cat isn't much more than unscrewing some bolts, if that is what I will need to do. I haven't noticed any rattling when driving, and when I tapped the cat nothing rattled either. Is it likely that the cat will "recover", or is it time to drop the dough?



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 2, 2012, 12:47 PM

Post #4 of 9 (2187 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In

PO420 is nearly always going to be a bad cat. It's almost impossible to meet all the criteria that code requires any other way. I've only seen it be something else once and that one was a crack right in front of the cat but after the upstream sensor.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



GoatTamer
Novice

Jul 2, 2012, 1:53 PM

Post #5 of 9 (2179 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In


In Reply To
PO420 is nearly always going to be a bad cat. It's almost impossible to meet all the criteria that code requires any other way. I've only seen it be something else once and that one was a crack right in front of the cat but after the upstream sensor.


Thanks for the advice but, as mentioned above, I've read in a few places that a cat rarely goes bad for no reason. I want to fix the root causes so that I don't replace the cat just to have the new one burn out 6 months later.


(This post was edited by GoatTamer on Jul 2, 2012, 1:54 PM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 2, 2012, 2:35 PM

Post #6 of 9 (2173 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In

293K is a reason




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



GoatTamer
Novice

Jul 2, 2012, 2:38 PM

Post #7 of 9 (2169 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In


In Reply To
293K is a reason

Absolutely. Any chance that the rich fuel mixture could have something to do with it though?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 2, 2012, 3:31 PM

Post #8 of 9 (2161 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In

Of course, if it really was rich. You didn't have any codes indicating that.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



GoatTamer
Novice

Jul 2, 2012, 6:31 PM

Post #9 of 9 (2150 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In

Thanks for your time!




Advertising


  Email This Post
 
 






Latest Forum Post

I apologize I have not got a lot of time in it so far, so I do not have a lot of...


I have a 1992 ford ranger 3.0l v6 5 speed. today i ran out of gas and when i got...


Hey people, Just as soon as I've got rid of one car and got another, I've got a...


Hello I have a 1993 Toyota Corolla w/1.8L and 3 sp +overdrive tranny. I took it ...


2008 Nissan Sentra 2.0 50000 Miles The trunk wouldn't open neither with the rem...


on a 1998 Chrysler cirrus the heater blows warm thru the vents. When u turn it o...


Feed Button






Automotive Forum Categories
AC Auto Repair
Auto Body Repair
Auto Insurance
Automotive Repair
Automotive Wiring
Automotive World
Brake Systems
Car Care Tips
Car Racing
Car Shows and Events
Car Stereo Repair
Car Troubleshooting
Engine and Car Noises
Engine Fault Codes
Engine Troubleshooting
Exhaust System Repair
Gasoline and Motor Oils
General Discussions
Motor Vehicle Inspection
Motorcycle ATV Repairs
Motorcycle Body Repair
Motorcycle Clutch Repair
Motorcycle Engine Repair
Motorcycle Repair
Motorcycle Seat Repair
Remote Control Cars
Steering and Suspension
The Bargin Bin
Traffic Ticket Help
Tricks of the Trade
Truck Repair
Truck Repair Advice
Truck Engine Repair
Truck Suspension Repair
Car Forum - Sitemap


Search for (options) Privacy