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 (2082 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


Jul 2, 2012, 11:22 AM

Post #2 of 9 (2067 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 (2053 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


Jul 2, 2012, 12:47 PM

Post #4 of 9 (2037 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 (2029 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


Jul 2, 2012, 2:35 PM

Post #6 of 9 (2023 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 (2019 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


Jul 2, 2012, 3:31 PM

Post #8 of 9 (2011 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 (2000 views)
Shortcut
Re: 1996 Honda Accord P0420 Causes? [In reply to] Sign In

Thanks for your time!




1996 Honda Accord P0420 Causes?


  Email This Post
 
 






Latest Forum Post
2008 Nissan Sentra 2.0 CVT 50,000 Miles New to DIY auto repair. I want to repla...
2003 Ford Wind Star SEL 3.8 6 cylinder 143,000 miles When shifter is in drive a...
I have a 1996 Chrysler Sebring that is overheating.. I would hear it bubbling b...
Hello all. I am going to take my car into the shop to see if they can help me di...
Hi there everyone, I just want to know could a bad brake muster cylinder cause t...
Brakes started getting bad (spongy, pedal to the floor). Checked all, pads good ...

Feed Button


Used Car Search
Used Car Price Ranges:
Under $5,000
$20,000
$35,000

$10,000
$25,000
$40,000
$15,000
$30,000
$45,000
Over $45,000
Search used Cars By Manufacturers:
Used Acura
Used Audi
Used BMW
Used Buick
Used Cadillac
Used Chevrolet
Used Chrysler
Used Dodge
Used FIAT
Used Ford
Used GMC

Used Honda
Used Hyundai
Used Infiniti
Used Jaguar
Used Jeep
Used Kia
Used Land Rover
Used Lexus
Used Lincoln
Used Mazda
Used Mercedes-Benz

Used MINI
Used Mitsubishi
Used Nissan
Used Porsche
Used Saab
Used Scion
Used Subaru
Used Suzuki
Used Toyota
Used Volkswagon
Used Volvo
2010 Honda Civic
$15,770
2004 Jeep
$8,991
2012 Mustang
$22,990
1997 Honda Cr-V
$4,490
2010 Toyota Prius
$17,496
2010 BMW 328
$26,980




Automotive Forum Categories
Automotive Repair
Auto Body Repair and Refinishing
AC Auto Repair Help Forum
Automotive Wiring and Electrical

Auto Insurance and Car Financing
Automotive World
Brake Systems
Car Stereo Repair Advice
Car Troubleshooting
Engine and Car Noises
Engine Fault Codes
Engine Troubleshooting
Exhaust System Repair

Steering and Suspension
Tricks of the Trade
General Discussions
Car Shows and Events
The Bargin Bin
Motor Vehicle Inspection
Car Care Tips
Traffic Ticket Help
Car Racing

Gasoline, Motor Oils, Concept Cars
Remote Control Cars and Vehicles
Truck Repair
Truck Repair Advice


Truck Engine Repair
Truck Suspension Repair
Motorcycle Repair
Motorcycle and ATV Repairs

Motorcycle Body Repair
Motorcycle Clutch Repair
Motorcycle Engine Repair
Motorcycle Seat Repair
Car Forum Posts - Sitemap


Search for (options) Privacy