Honda Prelude Forum
 
Go Back   Honda Prelude Forum > Tech-Talk > 5th Gen Honda Prelude

Thread Title
what code is this! p0420

 
Reply
 
LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old 06-06-2010, 03:05 AM
tuner357's Avatar
Silver Member
 
Join Date: May 2010
Location: Saskatoon, Saskatchewan
Posts: 300
iTrader: (0)
tuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond reputetuner357 has a reputation beyond repute
Send a message via MSN to tuner357
what code is this! p0420

please help
__________________

1999 Honda Prelude Type SH
6000k HID's, Fogs, Intake, Skunk2 cat back, Test pipe, Tein lowering springs(still need to install), jdm lip
Check me out: http://www.preludezone.com/members-r...99-typesh.html
Reply With Quote
  #2 (permalink)  
Old 06-06-2010, 04:09 AM
havikprelude's Avatar
Platinum Member
 
Join Date: May 2010
Location: New Jersey
Posts: 1,477
iTrader: (0)
havikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond repute
Re: what code is this! p0420

...nah, too easy.

To start with, Pxxx codes are powertrain, Bxxx codes are body related, Cxxx codes are chassis and Uxxx codes are are network DTC's.

Yours is powertrain. Also:

P0100 codes are air metering and fuel system faults
P0200 codes are fuel system (fuel injector only) faults
P0300 codes are ignition system or misfire faults
P0400 codes are emission control system faults
P0500 codes are idle speed control, vehicle speed sensor faults

Yours is emission related. Specifically, code P0420 means Catalyst System Efficiency Below Threshold (Bank 1). Which means the readings from the o2 sensors are similar, when the front one should be fluctuating and the rear one should be fairly steady.

For the most part, it means your cat isn't working like it should.
Which may have been caused by one or more of the following:
•Leaded fuel was used where unleaded was called for
•An oxygen sensor is not reading (functioning) properly
•The engine coolant temperature sensor is not working properly
•Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
•Retarded spark timing
•The oxygen sensors in front and behind the converter are reporting too similar of readings

Possible solutions include:
•Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
•Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
•Inspect the downstream heated oxygen sensor (HO2), replace if necessary
•Replace the catalytic converter



This was mostly taken from www.obd-codes.com. Google search FTW




To help you find the problem, riddle me this:

1. When was the last time you cleaned your air filter? Changed your spark plugs? Changed your o2 senors? Replaced your cat?
2. How old is the car?
3. What type of gas do you use?
4. Is the exhaust on your car stock or aftermarket? Is it loud or quiet?
5. Does your car make a rattling noise sometimes when its at idle or when you shut your car door?


Answer all questions completely and to the best of your ability. This will help us find your problem so you can get to fixing it.
__________________

Battery, Starter and Alternator Testing Procedures
Problems starting engine? | 5th gen resource

Quote:
Originally Posted by 1BadBB6 View Post
You're such a whiny little douche sometimes, but posts like these make me love you.

Last edited by havikprelude; 06-06-2010 at 04:17 AM.
Reply With Quote
  #3 (permalink)  
Old 06-14-2010, 08:07 PM
I'm New
 
Join Date: Jun 2010
Posts: 21
iTrader: (0)
Favio is on a distinguished road
Re: what code is this! p0420

I have the same code. What's the difference between an upstream and downstream O2. I was looking at oxygensensor123.com.
Reply With Quote
  #4 (permalink)  
Old 06-14-2010, 11:25 PM
Bustr's Avatar
Platinum Member
ROTM!
 
Join Date: Aug 2006
Location: ny
Posts: 1,388
iTrader: (9)
Bustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond reputeBustr has a reputation beyond repute
Send a message via AIM to Bustr
Re: what code is this! p0420

QUICK FIX. go to the auto parts store... buy yourself two spark plug non foulers that fit your 02 sensor. part number 42009 i believe. you have to drill out one to make the o2 fit... bore it out you will know what i am talking about. then screw them both in... obviously the non fabricated one then the fabricated one and finally your secondary o2. plug your secondary o2 back in. reset your computer .... under hood fuse box fuse is 7.5 labeled clock/radio fuse.... pull it out wait 5 seconds plug it in and start her up.

when you get cat efficiency codes.... it means your o2 are reading to similar. cat is going bad... so if you make your second o2 read a totally different reading from your primary o2.... the computer will not see an error. hope this helps guys.
__________________
MY ALL MOTOR?<.....click


MY TURBO ?<.....click

NEVER TELL ME IT CAN"T BE DONE
Reply With Quote
  #5 (permalink)  
Old 06-15-2010, 01:08 AM
CTLude's Avatar
Gold Member
 
Join Date: Dec 2009
Location: Connecticut
Posts: 734
iTrader: (0)
CTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond repute
Send a message via AIM to CTLude
Re: what code is this! p0420

You need a new cat plain and simple!
Reply With Quote
  #6 (permalink)  
Old 06-15-2010, 10:51 AM
BB6LudeAtic's Avatar
I'm New
 
Join Date: Apr 2009
Location: DFW,Tx
Posts: 18
iTrader: (0)
BB6LudeAtic is on a distinguished road
Re: what code is this! p0420

Quote:
Originally Posted by Bustr View Post
QUICK FIX. go to the auto parts store... buy yourself two spark plug non foulers that fit your 02 sensor. part number 42009 i believe. you have to drill out one to make the o2 fit... bore it out you will know what i am talking about. then screw them both in... obviously the non fabricated one then the fabricated one and finally your secondary o2. plug your secondary o2 back in. reset your computer .... under hood fuse box fuse is 7.5 labeled clock/radio fuse.... pull it out wait 5 seconds plug it in and start her up.

when you get cat efficiency codes.... it means your o2 are reading to similar. cat is going bad... so if you make your second o2 read a totally different reading from your primary o2.... the computer will not see an error. hope this helps guys.

Do this! It works great I have had this on my car for 1.5 years and no more CEL P0420
__________________
Reply With Quote
  #7 (permalink)  
Old 06-15-2010, 11:07 AM
I'm New
 
Join Date: Jun 2010
Posts: 21
iTrader: (0)
Favio is on a distinguished road
Re: what code is this! p0420

Someone said that this is only done when you have a testing pipe. Is that correct, or can you do it with the cat in?
Reply With Quote
  #8 (permalink)  
Old 06-15-2010, 11:07 AM
Bronze Member
 
Join Date: Mar 2010
Posts: 178
iTrader: (1)
jkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond reputejkoni426 has a reputation beyond repute
Re: what code is this! p0420

that means it's time for u and your car to smoke out

lol but seriously, that means u need to replace your cat. or if u have a test pipe on there u need to do the non fouler trick.
__________________
'96 BB1- sold, no longer luding

"The value of life can be measured by how many times your soul has been deeply stirred."

-Soichiro Honda
Reply With Quote
  #9 (permalink)  
Old 06-15-2010, 11:09 AM
I'm New
 
Join Date: Jun 2010
Posts: 21
iTrader: (0)
Favio is on a distinguished road
Re: what code is this! p0420

Ok thanks for your help.
Reply With Quote
  #10 (permalink)  
Old 06-15-2010, 12:09 PM
havikprelude's Avatar
Platinum Member
 
Join Date: May 2010
Location: New Jersey
Posts: 1,477
iTrader: (0)
havikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond reputehavikprelude has a reputation beyond repute
Re: what code is this! p0420

Quote:
Originally Posted by Bustr View Post
QUICK FIX. go to the auto parts store... buy yourself two spark plug non foulers that fit your 02 sensor. part number 42009 i believe.
Correct
Quote:
you have to drill out one to make the o2 fit... bore it out you will know what i am talking about.
Drill out one of the anti-foulers, down the middle to 1/2 inch. Don't mess up the threads.
Quote:
then screw them both in... obviously the non fabricated one then the fabricated one and finally your secondary o2.
The order goes- o2 sensor>drilled fouler>stock fouler>cat
Quote:
plug your secondary o2 back in. reset your computer .... under hood fuse box fuse is 7.5 labeled clock/radio fuse.... pull it out wait 5 seconds plug it in and start her up.
It's ten seconds. And before you pull it make sure you have your radio activation code, othewise enjoy listening to wind.
__________________

Battery, Starter and Alternator Testing Procedures
Problems starting engine? | 5th gen resource

Quote:
Originally Posted by 1BadBB6 View Post
You're such a whiny little douche sometimes, but posts like these make me love you.

Last edited by havikprelude; 06-15-2010 at 12:12 PM.
Reply With Quote
  #11 (permalink)  
Old 06-16-2010, 06:07 PM
Bronze Member
 
Join Date: Apr 2010
Posts: 136
iTrader: (0)
chriscor08 is on a distinguished road
Re: what code is this! p0420

get a new cat or go get a test pipe!
Reply With Quote
  #12 (permalink)  
Old 08-18-2015, 06:42 PM
I'm New
 
Join Date: Feb 2015
Location: Colorado
Posts: 5
iTrader: (0)
SupsLude is on a distinguished road
Re: what code is this! p0420

Hey everyone, I'm getting the same code ! I've got an aftermarket
Exhaust with a magnaflow cat . Both are less than 6 months old with less than a thousand miles on em(both o2 sensors replaced at the same time) because shortly after I installed them I rebuilt the engine (top, bottom and side to side. Lol) and had some issues getting parts and of course the timing belt was a pain in the ass (still not satisfied with it) . My problem seems like more than the exhaust, my idle is really screwy . When I'm in motion and I go to slow down and I push in the cluch or put it in neutral the idle drops way low and even dies some times . The idle is never consistent. Any kind of input will be greatly appreciated.

Everything I can remember that has been done besides the rebuild. If its internal, I've done it! (I hope, lol)

Plugs and wires
Cap and rotor
Coil
Egr valve and solenoid
Exhaust
Crank position sensor
Throttle position sensor
Knock sensor
Oil pressure sensor
Complete teardown and cleaning of throttle body, intake manifold, FIC, and IACV
Fuel injectors cleaned and new seals
Probably more , but what can you do
Thanks for the read
Reply With Quote
  #13 (permalink)  
Old 06-14-2016, 03:23 PM
I'm New
 
Join Date: Jun 2016
Posts: 4
iTrader: (0)
Ducky is on a distinguished road
Re: what code is this! p0420

Thanks, this is helpful.
Reply With Quote
  #14 (permalink)  
Old 06-14-2016, 05:34 PM
CTLude's Avatar
Gold Member
 
Join Date: Dec 2009
Location: Connecticut
Posts: 734
iTrader: (0)
CTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond reputeCTLude has a reputation beyond repute
Send a message via AIM to CTLude
Re: what code is this! p0420

Quote:
Originally Posted by Bustr View Post
QUICK FIX. go to the auto parts store... buy yourself two spark plug non foulers that fit your 02 sensor. part number 42009 i believe. you have to drill out one to make the o2 fit... bore it out you will know what i am talking about. then screw them both in... obviously the non fabricated one then the fabricated one and finally your secondary o2. plug your secondary o2 back in. reset your computer .... under hood fuse box fuse is 7.5 labeled clock/radio fuse.... pull it out wait 5 seconds plug it in and start her up.

when you get cat efficiency codes.... it means your o2 are reading to similar. cat is going bad... so if you make your second o2 read a totally different reading from your primary o2.... the computer will not see an error. hope this helps guys.

This Actually works MINT!! Just did it on mine and passed emissions with flying colors and the light still hasn't came back on!

Quote:
Originally Posted by BB6LudeAtic View Post
Do this! It works great I have had this on my car for 1.5 years and no more CEL P0420
I Bet!

Quote:
Originally Posted by Favio View Post
Someone said that this is only done when you have a testing pipe. Is that correct, or can you do it with the cat in?
My OEM cat is in and it is working like a charm!

Quote:
Originally Posted by jkoni426 View Post
that means it's time for u and your car to smoke out

lol but seriously, that means u need to replace your cat. or if u have a test pipe on there u need to do the non fouler trick.
Definitely,...Everyday!.. I don't have the 420 code anymore but still treat her KIND!!! !!! lol
__________________
~92 Accord EX 5 speed.
~98 Base Prelude. Auto, very soon to be 5 speed.
...................5 Speed Swap Complete!!..................

http://www.preludezone.com/5th-gen-h...-complete.html



~98 Base Prelude- Now 5 Speed swapped and very soon JDM H22A swap

**JDM H22A with only 42k miles swap complete!!
Reply With Quote
Reply

Tags
p0420


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
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
P0420 - How to proceed? cylord 5th Gen Honda Prelude 14 01-29-2010 10:16 PM
help! code 45 and 15 93prludeSi General Tech Talk 2 11-29-2009 07:04 PM
code 111 and 13? Kronicus 4th Gen Honda Prelude 6 04-26-2009 01:52 PM
CEL code p0420 (lol 420) yogi_pahl General Tech Talk 4 03-24-2008 08:24 PM
CEL code(s) 00CDMLUDER 5th Gen Honda Prelude 1 12-05-2007 04:49 PM


All times are GMT -4. The time now is 09:10 PM.



Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
LinkBacks Enabled by vBSEO 3.6.0 PL2 © 2011, Crawlability, Inc.
vB.Sponsors


Copyright © 2006-2009 PreludeZone.com All Rights Reserved.