P0420 engine code [Archive] - Honda Ridgeline Owners Club Forums

: P0420 engine code


wadeinde
11-22-2008, 12:41 AM
i have 112000 miles on my rts, everything runs as it should and all of a sudden my check engine light popped up, telling me.... catalist blah blah blah bank 1, in the past that meant oxygen sensor, (pre-cat).... anyone had this issue.

i erasaed the code and it hasent popped up yet,
any advice would be great, thank
w

ericrwalker
12-04-2008, 06:00 AM
I have the same code, I needed to pass inspection....my mechanic told me I needed a new "bank1" cat. I took it to Honda they told me the same...I bought a new cat and the light still comes on.

I took it for inspection again and my mechanic (not Honda) told me that Honda replaced the wrong cat...in fact they replaced one that doesn't even have a sensor on it.

I am going to call them this morning about it.

Ridgekid
12-04-2008, 06:24 AM
P0420: Rear Bank Catalyst System Efficiency Below Threshold(Bank 1)
There is a test proceedure to see if the problem is intermittent or steady. If steady, the rear WU-TWC needs to be replaced (catalytic converter).
After replacement, the re-learn proceedure should be followed to reset the ECM.
Make sure all lectrical accessories are off (AC, lights radio, etc)
Reset the PCM with the HDS (if you don't access to the HDS, there is a manual method that requires disconnecting the battery)

Turn iginition to on for 2 seconds (dont crank the motor)
Start the motor and run at 3000 rpm until the radiator fan comes on.

Idle the motor for 5 minutes ( don't touch the gas pedal)

If the fan comes on again, dont count the time it is running as part of the 5 minutes ( so if the fan comes on for 30 seconds every 2 minutes, you will run for about 6 1/2 minutes total)

Cochise111
12-04-2008, 07:37 AM
I'm not a Honda technician, but I was a Lexus technician. The cats rarely fail. 99% of the time when we got a inefficient cat code, it was the sensor. Oxygen sensor. If it came on immediately after the code was cleared, it was usually a short in the heating circuit. Change the sensor, and no more problems.

ericrwalker
12-04-2008, 07:49 AM
I wonder why it failed emissions then...or maybe it failed because the truck computer told them it was bad.

Ridgekid
12-04-2008, 08:37 AM
It is possible that the sensor is bad or possible dirty. If the sensor is open or shorted, it will throw a different code either P137, 138, 139 or p141.

ericrwalker
12-04-2008, 08:52 AM
hmmm, well I am going to the dealer in an hour...the service woman told me that there is only 1 cat that can be replaced...and that's the one that was done.

I find it funny that there are sensors on the 2 warm up cats (that can't be replaced, according to her) but no sensors on the one they replaced.

Ridgekid
12-04-2008, 04:36 PM
hmmm, well I am going to the dealer in an hour...the service woman told me that there is only 1 cat that can be replaced...and that's the one that was done.

I find it funny that there are sensors on the 2 warm up cats (that can't be replaced, according to her) but no sensors on the one they replaced.

That woman may not be up to date..
In the manual there is a page for front cat replacement and rear bank replacement. In addition, Each converter has two O2 sensors.

Maybe she needs TRFM.

xridgelinex
12-04-2008, 04:56 PM
hmmm, well I am going to the dealer in an hour...the service woman told me that there is only 1 cat that can be replaced...and that's the one that was done.

I find it funny that there are sensors on the 2 warm up cats (that can't be replaced, according to her) but no sensors on the one they replaced.

I prescribe a tank filled with high test with 2- 12 ounce bottles of Techron and run through the tank going up and down the big hill on route 7. Be sure to floor it and get that v-tec kicking in... This should clean out the system and loosen and burn off the deposits.

If all else fails, at least you had some fun and cleaned out the fuel lines and injectors.

Which dealer are you using?

Ridgekid
12-05-2008, 05:51 AM
I prescribe a tank filled with high test with 2- 12 ounce bottles of Techron and run through the tank going up and down the big hill on route 7. Be sure to floor it and get that v-tec kicking in... This should clean out the system and loosen and burn off the deposits.

If all else fails, at least you had some fun and cleaned out the fuel lines and injectors.

Which dealer are you using?

Thta's not going to clean the O2 sensors in the cats. It may make them dirtier.
If the cats are bad or one is bad, it usually is caused by one of two things: Raw gas / very rich mixture passed into the exhaust system or leaded fuel was used ( or possibily contaminated fuel). That might include some additives. I recommend that fuel additives don't be used.
One thing you could try if you have the time and energy is to remove both O2 sensors from each cat, clean them and swap them , front bank to back bank
If the code changes from p0420 to p0430, one or both of the swapped sensors is faulty. If p0420 pops up again, it is either the cat itself or a connector, wire, ECM (!!!) issue.

CUinaRidge
12-13-2008, 01:40 PM
http://www.ridgelineownersclub.com/forums/showpost.php?p=357780&postcount=17

Update: Both vehicles had the 420 code. Catalytic replaced under warranty with the civic. Code went off by the time I took the RL in, Code checked stored was 420 & 463 fuel sensor in the tank. After a week the emmision light just came back on.

Will have to take the RL back in...

wadeinde
12-13-2008, 04:21 PM
well keep in mind, its winter, anywere it gets cold is switching to "winter gas". basicly alittle more alcohol, conbined with all this ethonol that internal conbuston engines just LOVE! is a contributing factor. i have come to the conclutsion at least in my case that its the cat, not a O2 sensor, because mine comes and goes. mostly after hard acceleration or during towing, if it was an O2 sensor it would always be on. (i have alittle experiance in the area, my cars have always had one problem or another):D

ima just go the cheap route weld on a cat myself, but thanks for all your imput i guess i have a honda im allowed one problem;)

Ridgekid
12-13-2008, 04:51 PM
http://www.ridgelineownersclub.com/forums/showpost.php?p=357780&postcount=17

Update: Both vehicles had the 420 code. Catalytic replaced under warranty with the civic. Code went off by the time I took the RL in, Code checked stored was 420 & 463 fuel sensor in the tank. After a week the emmision light just came back on.

Will have to take the RL back in...

I'll bet you a nickle that you bought gas for both vehicles at the same station.

CUinaRidge
12-13-2008, 11:18 PM
I'll bet you a nickle that you bought gas for both vehicles at the same station.

Your nickle wins!! yep it was at a Shell station.

I think I am going to run a few tanks of Premium through, see if the light goes off again.

:)

atikovi
12-14-2008, 05:20 PM
Any opinion on using one of these devices to keep the CEL off: http://store.kteller.biz/product.asp?s=owgklf19701&strParents=&CAT_ID=0&P_ID=937&strPageHistory=search&numSearchStartRecord=1

If it can keep the light from coming on with no cat, it should surely keep it off if you do have a cat thats just tired. It basically moves the O2 sensor away from the direct exhaust stream thus it doesn't sense all the HC's so it won't trigger a P0420/P0430 code. Obviously if your cat has had a melt down it won't help but if its just triggering the code now and then from old age, it may help you put off replacing the cat if you need a emissions inspection.

CUinaRidge
12-14-2008, 11:35 PM
... I think I am going to run a few tanks of Premium through, see if the light goes off again.

Put in 1/2 tank Premium, light went off again.

:)

Ridgekid
12-18-2008, 03:31 PM
If the gas was really bad, contaminated or had lead in it, the Cat Cvrt is fried.

Spydr26
12-28-2008, 04:45 PM
My '06 ridgeline with 190,000 km's on it just posted this code today.
I cleared the code with my code reader but also noted that I have an Evaporative system monitor not responding.
I took the truck for a ride after clearing the code and it hasn't returned yet.
Not sure if these are related, might try the dealership to see what they have to say.

wrenrj1
12-28-2008, 06:22 PM
I prescribe a tank filled with high test with 2- 12 ounce bottles of Techron and run through the tank going up and down the big hill on route 7. Be sure to floor it and get that v-tec kicking in... This should clean out the system and loosen and burn off the deposits.

Or just move to a state that doesn't require emissions checks, and possibly lower taxes...

CUinaRidge
01-06-2009, 04:39 PM
Update: After 1 week the light came back on for 1 day. The light has not been on since. I have been filling the RL consistantly since the 1st incident with premium.

Question: Has there been any damage done that would affect future engine performance? Would there be any reason to replace the cat or the o2 sensor?

ramblinwreck
03-05-2009, 06:14 AM
Hey all- new member here. Got RTL with 93,993 miles on it and now getting the 420 code on bank 1. is there anyway to tell whether the downstream or upstream o2 sensor should be replaced, or should they be replaced in tandem? I wanted to this before investing in a new cat....was going to go with ngk sensors if available...are these any better than the bosch sets? thanks for your input!

Just Ask
03-05-2009, 11:40 AM
Hey all- new member here. Got RTL with 93,993 miles on it and now getting the 420 code on bank 1. is there anyway to tell whether the downstream or upstream o2 sensor should be replaced, or should they be replaced in tandem? I wanted to this before investing in a new cat....was going to go with ngk sensors if available...are these any better than the bosch sets? thanks for your input!

Try switching just the upstream one with a sensor from bank 2. If you still get 420, then you know it's the downstream one on Bank 1. If you get a 430 (I think that's the one for Bank 2) then you know it's the upstream one (now) in bank 2. No need to pay for two if only one is bad - they aren't cheap nor returnable.

ramblinwreck
03-05-2009, 01:09 PM
Thanks for the response! That makes a ton of sense. Any ideas as to what brand to get if i replace?

Just Ask
03-05-2009, 08:37 PM
Thanks for the response! That makes a ton of sense. Any ideas as to what brand to get if i replace?

I would go with whatever Honda OEM is...the first one was good for 93k miles ya know :-)

TeamRidgeline
03-09-2009, 05:14 PM
Looks like I just joined the club ...

http://www.ridgelineownersclub.com/forums/showthread.php?t=26867

starfixer
01-01-2010, 09:50 PM
ok now have had this twice but last time reset it and changed gas to premium ran for around 2000 miles and just popped on again on the way home. Had decided to try 87 oct again about 2 tanks back and yesterday filled up with 93+. My dilemma is this if I take it to Dealer are likely to look at it charge me and then say it is a tank of gas after resetting it. They really do not like to do anything that may or may not be under warranty, and I thought there was an 80000 mile emissions warranty, but when looked up the info on fed site and honda states manufacturers usually cover it underpowertrain and Honda states 3yr 36000 for the powertrain. any body know of anywhere in particular that has the federal guidelines that state otherwise? I do not want to pay for a deductble on the extended warranty for them to do nothing per say. Or am I just worrying to much and it is just the winter mixture again. I wouldnt mind changing the sensors out and checking them if I could, but I have done the unthinkable ( I have not purchased a book!). LOL I have been meaning to but yeah I know. I would appreciate any suggestions. Or think I should try to argue with the dealer and see if they will cover the sensors/Cat? btw 62000 miles. thanks

CUinaRidge
01-02-2010, 08:11 AM
Mine came back on in December, filled the tank up and the light went off. It has not been on since...

Jack
01-02-2010, 08:59 PM
Where I am in Virgina, or Taxginia as we call it, this is the scam they use. 1st they drive your car into the stall and if any lights are on you automatically fail but have to pay. Then you get a waiver to fix it. If they drive it into the stall and there are no lights but they connect to the computer and it shows a code, stored, whatever, automatic fail and repeat waiver process.

On older cars, usually pre 1996, they put the probe in your tailpipe (that sounds weird) and test the actual emissions, which is way more accurate IMO.

The old method gave you a range and if your emissions were in that range then you were fine. If not then a fail. The computer does not give you a snowballs chance in hell. A bad sensor can cause a fail when your car is actually withing established limits.

Just another way to screw ya!

comquat1
01-23-2012, 08:33 PM
Just got this code the other day along with some others. Went and bought a code reader that can reset them and did that the following day and drove all day today and it did not come back on.

One thing I noticed is typically my truck is driven all day and rarely goes out at night. The night it went on I went out and the truck was parked outdoors in temps below 20 degrees and it went on when I was on my way back home.

I've noticed a few oddities with my ridge (and 06 of which i'm the original owner) the last couple months when it's bitterly cold out. I'm seeing the airbag light go on and off also, when it warms back up it goes off again.

I'm thinking if this truck was kept outdoors regularly that I'd be having way more issues with it than I've had, which up until the last month was zero issues in 166,000 miles.

carolinaridgeline
01-24-2012, 12:24 AM
I have been getting this code for about six months now and the code reader indicates Bank 1. I am not sure if this is the CAT between the radiator and engine or the one between the bulkhead/firewall and engine. Can anyone tell me? I continue to reset it and it comes on every couple of weeks. Now, my Ridge has 138,000 miles on also. Do I need to stay with OEM CAT or is there a a pretty good aftermarket CAT I can use?

speedlever
01-24-2012, 06:56 AM
Bank 1 is the rear one.

http://i.imgur.com/dqXyH.png

carolinaridgeline
01-24-2012, 09:25 AM
You are Awesome speedlever! Thank you for the clear detail. Any comment on OEM replacement versus aftermarket?

speedlever
01-24-2012, 09:31 AM
Sorry, I don't know about that. My daughter recently had to have her Pilot's cats replaced in the 116k mile range and the mechanic (local guy, not a dealer) went with OEM over aftermarket... but I don't recall why.

comquat1
01-24-2012, 08:01 PM
Why doesn't that look like it's real easy to get up into? Or am I wrong?

I'm on day two of of no return of the light. Temps have been warm, around freezing and the truck has not been sitting not running in the cold for any extended amount of time. I don't know if i'm onto something or not, just an odd theory as when my light came on that my truck was used at a different time.

speedlever
01-24-2012, 08:20 PM
I suspect it's not easy to get to. I know the mechanic that did my daughter's Pilot said the rear one was a beyatch to do... or words to that effect. I bet the RL is similar.

comquat1
02-07-2012, 01:45 PM
does anyone have the part number for the rear bank cat? I want to make sure my dealer isn't fleecing me.

Just did some searching.... is it this? 18290-RJE-A00

RowlettRidgeline
02-08-2012, 08:31 AM
I got LUCKY!

I got the P0420 code at 89,000 miles in my 06 Ridgeline RTL. I Googled the code which led me to this forum. I read that some people experienced success with simply filling the tank with premium fuel and driving a few hundred miles.

On the way home the day I read the posts, I stopped at Chevron and filled up with their premium 93 Octane fuel. I drove for a few days and the light remained illuminated. It was only after I drove on the highway for 50 miles that the light went out. The stop and go traffic I sit in daily was not enough to turn the light out but the sustained highway driving did the trick.

So, if you have this code, try this before you give in and buy a new catalytic converter.

My .02

Steve

Ourfarm09
02-08-2012, 04:55 PM
I got LUCKY!

I got the P0420 code at 89,000 miles in my 06 Ridgeline RTL. I Googled the code which led me to this forum. I read that some people experienced success with simply filling the tank with premium fuel and driving a few hundred miles.

On the way home the day I read the posts, I stopped at Chevron and filled up with their premium 93 Octane fuel. I drove for a few days and the light remained illuminated. It was only after I drove on the highway for 50 miles that the light went out. The stop and go traffic I sit in daily was not enough to turn the light out but the sustained highway driving did the trick.

So, if you have this code, try this before you give in and buy a new catalytic converter.

My .02

Steve


Glad it worked out for you.

Welcome to the club...

xd9x19
11-01-2012, 11:16 AM
I got LUCKY!

I got the P0420 code at 89,000 miles in my 06 Ridgeline RTL. I Googled the code which led me to this forum. I read that some people experienced success with simply filling the tank with premium fuel and driving a few hundred miles.

On the way home the day I read the posts, I stopped at Chevron and filled up with their premium 93 Octane fuel. I drove for a few days and the light remained illuminated. It was only after I drove on the highway for 50 miles that the light went out. The stop and go traffic I sit in daily was not enough to turn the light out but the sustained highway driving did the trick.

So, if you have this code, try this before you give in and buy a new catalytic converter.

My .02

Steve
I think that may be because one part of the test procedures to determine if the issue is intermittent or continual involves driving the Ridgeline at highway speeds for a number of miles. Per the service manual, that is part of the test procedure.

My Ridgeline threw the P0420 code yesterday 10 miles after I filled up the gas tank. I think I'm going to just clear the code and fill up the tank at a different station and see if it comes back on.

In the past, I've had the check engine light come on only to have it go after after 1 or 2 tanks of gas. I'm hoping the same will be true here. Replacing the cat doesn't look like a cheap job. The Auto-zone version runs $250-300, so I figure getting an independent shop to do it probably means $600-800.

Anybody got any cost quotes, estimates or done it yourself?

******
UPDATE: cleared the code yesterday and have driven the Ridgeline 70 or so miles so far and the light hasn't come back on.

xd9x19
11-06-2012, 07:49 AM
:mad: Driving to work this morning and the check engine light came back on. I filled the Ridgeline up yesterday at a different station on the other side of town and was about 50 miles into this tank and on the interstate again. I'm assuming it's going to be the same P0420 code, but will have to wait until I get home tonight to plug in my scanner and confirm.

If it is the same P0420 code, then it's popped up under similar circumstances:
1) within 50 miles of filling the tank
2) driving down the interstate between 60 and 70

As I stated in my previous post, I cleared the code last week and drove another 250 or so miles on that tank of gas without it coming back on.

xd9x19
11-13-2012, 01:19 PM
Code came on again about 250 miles into the tank of gas...again, while on a segment of expressway while doing between 60 and 70. Cleared the code again and filled with premium (93) from a BP/Amoco station.

About 120 into the tank of premium and several trips on the same segment of (in-town) expressway and no code yet.

1stgen
11-30-2012, 11:47 PM
What do you guys think of this?

http://www.youtube.com/watch?v=5icTmYItwiE

Code came on again about 250 miles into the tank of gas...again, while on a segment of expressway while doing between 60 and 70. Cleared the code again and filled with premium (93) from a BP/Amoco station.

About 120 into the tank of premium and several trips on the same segment of (in-town) expressway and no code yet.

I got my first P0420 code about 260 miles ago. I reset it and it came back today.

Should I try the 91-93 octane gas first?

JAC
01-05-2013, 09:13 AM
I got this code about 2 weeks ago at 72,000 miles. Turnersville told me the same thing, cat bank 1. The light went out after coming home from the dealer but they already ordered the new cat, and they said it was under warranty so today they are replacing it. Fed emissions warranty is 80,000 miles or 8 yrs, might as well let them replace the hard one to get to!

xd9x19
01-05-2013, 02:43 PM
What do you guys think of this?

http://www.youtube.com/watch?v=5icTmYItwiE



I got my first P0420 code about 260 miles ago. I reset it and it came back today.

Should I try the 91-93 octane gas first?
I tried a tank of 93. Didn't work. I've had to reset/clear the code about once every tankful of gas since it originally came on...about every 250-300 miles.

R_Foundation
04-02-2013, 07:28 AM
Hello I just got the 420 code yesterday, I have a little over 148,000 on my Ridge :act035:. I filled up with Chevron 87 and put a can of BG44K in. I drove around yesterday for about an hour with the light on. Did a little hwy but mostly city streets. Started her up this morning and the code went away. I will keep you guys updated if the code comes back.

xd9x19
05-31-2013, 08:24 AM
Interesting development at the moment. After a few months of clearing out the P0420 code about once per tank of gas, I've now gone through about two tanks of gas without the engine light coming on. I'd read some folks had this happen when the weather got warmer, so I'm wondering if that is the case. Weather has changed here in Memphis from the 40s/50s overnight and 60s/70s in the day to 60s/70s at night and 80s during the day.

xd9x19
02-07-2014, 11:54 AM
Just dropping back in for an update. The light eventually came back on with the same P0420 code. I've just driven with it. It's gone out on it's own a couple of times, stays on mostly. If I feel like it, I'll clear the code just to see how long it takes to come back on. Usually within a tank or two.

Needing to get tires for the RL, so I won't be spending money to get an O2 sensor or cat within the next couple of months.

ace5000
02-20-2014, 11:04 AM
My P0420 engine code came on last winter when the temp dipped to 10 degrees F.
My local shop said they got a rash of codes with various cars during the cold because they have to work harder. My went off for the Spring and Summer only to return again this Winter...

I may try swapping the sensors to see what happens. Anyone get a deal on new sensors?