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post #46 of 71 Old 11-09-2011, 01:44 PM
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Cool P420 & p1399

Hello,
I also have been dealing with these issues. It began with P1399 and was told that the issue was my distributor, so I replaced it last week and now I am getting the P420 code. I don't understand that because I replaced my CAT about 20k ago and all was good till recently my CEL came on all the while the car ran fine at higher RPM's; however, at idle it would idle rough and my CEL would at times blink. So I have thus far replaced: Plugs, wires, COMPLETE DISTRIBUTOR (recommended by dealer), CAT (about 1.5 year ago).
Today I ran diagnostics and came up with the P1399 as well as P420. I have been reading and the only thing I have not done is replace O2's and EGR.

Anyone have more suggestions outside of this thread? Match and lighter fluid are not an acceptable repair! I have thought about it though!

Thanks,

Clem

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post #47 of 71 Old 11-09-2011, 02:35 PM
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Quote:
Originally Posted by autobahnclem View Post
Hello,
I also have been dealing with these issues. It began with P1399 and was told that the issue was my distributor, so I replaced it last week and now I am getting the P420 code. I don't understand that because I replaced my CAT about 20k ago and all was good till recently my CEL came on all the while the car ran fine at higher RPM's; however, at idle it would idle rough and my CEL would at times blink. So I have thus far replaced: Plugs, wires, COMPLETE DISTRIBUTOR (recommended by dealer), CAT (about 1.5 year ago).
Today I ran diagnostics and came up with the P1399 as well as P420. I have been reading and the only thing I have not done is replace O2's and EGR.

Anyone have more suggestions outside of this thread? Match and lighter fluid are not an acceptable repair! I have thought about it though!

Thanks,

Clem
Please specify your car exactly. Model (engine and transmission), year, current mileage, any service done to the engine at how many miles and years ago(valve clearance adjustmet, plugs etc.).
Then we can try to help you.


Honda Accord hybrid '07
without NAVI Silver 198k miles - sold
Honda Accord Touring '13 MSM
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post #48 of 71 Old 11-09-2011, 08:13 PM
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WOW! I actually didn't post that really important stuff, duh! I have a 2000 Accord EX 2.3 5 speed, 238k. No other info other than that.

Last edited by autobahnclem; 11-09-2011 at 08:14 PM. Reason: still missing info
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post #49 of 71 Old 11-10-2011, 08:29 AM
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When was valve clearance adjustment done the last time? If you don't know exactly when then I would strongly recommed to do it now.

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without NAVI Silver 198k miles - sold
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post #50 of 71 Old 11-10-2011, 12:15 PM
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Valve Adjustment

I have never done anything like that on a Honda, is it pretty much the same as on an american (chevy) v8? If so, what should the clearance be? Is there a specific order or proceedure in which to do this?
Thanks!
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post #51 of 71 Old 11-12-2011, 10:30 AM
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Okay,
I adjusted the valves back lash, they were at .22 intake and .25 exhaust. I adjusted these to .27 and .30.
Also, the very first thing I noticed is that the plugs were not very tight, by that I mean they just snug at best... wonder if that was the problem causing the P1399.
I also removed the EGR and checked it, it looked fine, no real obstructions on the ports.
Last, I scanned it and only came back with the P420 (bank 1). I'm going to drive and see what happens next, I'll keep you posted.
Thanks for info!

Clem
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post #52 of 71 Old 11-14-2011, 10:59 AM
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Okay,
38 miles later and my CEL is back. I just scanned it and the same P420 (bank 1). I am starting to think that I should replace the O2, but which?
Any ideas?

Thanks,

Clem
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post #53 of 71 Old 11-14-2011, 05:18 PM
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Hello Clem,

According to repair manual:

DTC P0420: Rear Bank Catalyst System Efficiency Below Threshold (Bank 1)
DTC P0430: Front Bank Catalyst System Efficiency Below Threshold (Bank 2)


NOTE:

•Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
•These catalysts are mounted to the cylinder head.
•If some of the DTCs listed below are stored at the same time as DTC P0420 and/or P0430*, troubleshoot those DTCs first, then recheck for DTC P0420 and/or P0430*. P0137, P0138, P0157, P0158, P2270, P2271, P2272*, P2273*: Secondary HO2S (Sensor 2)
P0141, P0161 *: Secondary HO2S (Sensor 2) heater

•Poor quality fuel can cause these DTCs.
•Information marked with an asterisk (*) applies to the front bank (Bank 2).
1.Turn the ignition switch ON (II).
2.Clear the DTC with the HDS.
3.Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
4.Test-drive under these conditions:
•ECT SENSOR 1 above 158°F (70°C)
•Transmission in D position
•Vehicle speed between 45 - 75 mph (72 - 120 km/h) for 5 minutes or more with cruise control set
•Maintain the vehicle speed at 55 mph (88 km/h) for 5 minutes or more with cruise control set
5.Monitor the OBD STATUS for DTC P0420 and/or P0430* in the DTCs MENU with the HDS. Does the screen indicate EXECUTING? YES - Go to step 6. NO - If the screen indicates OUT OF CONDITION, go to step 4 and recheck. If the screen indicates PASSED, intermittent failure, the system is OK at this time. If the screen indicates FAILED, go to step 8.
6.Continue test-driving until a result comes on.
7.Monitor the OBD STATUS for DTC P0420 and/or P0430* in the DTCs MENU with the HDS. Does the screen indicate FAILED? YES - Go to step 8. NO - If the screen indicates PASSED, intermittent failure, the system is OK at this time. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 4 and recheck.
8.Turn the ignition switch OFF.
9.Replace the WU-TWC
•For DTC P0420, replace the rear WU-TWC (Bank 1).
•For DTC P0430, replace the front WU-TWC (Bank 2).
10.Turn the ignition switch ON (II).
11.Reset the PCM with the HDS.
12.Do the PCM idle learn procedure. See: Programming and Relearning
13.Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
14.Test-drive for about 10 minutes, continually changing the vehicle speed.
15.Check the DATA MONITOR CONDITION B1/B2 in the DATA LIST with the HDS. Is the temperature OK? YES - Go to step 16. NO - Go to step 13 and recheck.
16.Test-drive under these conditions:
•ECT SENSOR 1 above 158°F (70°C)
•Transmission in D position
•Vehicle speed at 55 mph (88 km/h) for 5 minutes or more with cruise control set
17.Monitor the OBD STATUS for DTC P0420 and/or P0430* in the DTCs MENU with the HDS. Does the screen Indicate EXECUTING? YES - Go to step 18. NO - Go to step 16 and recheck.
18.Continue test-driving until a result comes on.
19.Check for Temporary DTCs or DTCs with the HDS. Are any Temporary DTCs or DTCs indicated? YES - Go to the indicated DTCs troubleshooting. NO - Go to step 20.
20.Monitor the OBD STATUS for DTC P0420 and/or P0430* in the DTCs MENU with the HDS. Does the screen indicate PASSED? YES - Troubleshooting is complete. NO - If the screen indicates FAILED, check the fuel quality. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 13 and recheck.

Sounds like you need a new catalytic converter. Here is another post about similar problem:

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without NAVI Silver 198k miles - sold
Honda Accord Touring '13 MSM
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post #54 of 71 Old 11-14-2011, 10:16 PM
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Even though mine has less than 30k on it?
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post #55 of 71 Old 11-15-2011, 01:48 PM
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Quote:
Originally Posted by autobahnclem View Post
Even though mine has less than 30k on it?
Yes. If there is a problem with your engine then you can kill a catalyst very quickly. That's why it is the best to do a comprehensive diagnostic on the engine.
But some vehicles are prone to burn CATs very quickly. Toyota 4Runner 2003 6-cyl is a good example (the bad EFI program is the cause for this).
If the valves were out of spec and you drove the car ignoring CEL then you burned excessive amount of fuel in your CATs and they gave up quickly.

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post #56 of 71 Old 12-26-2011, 07:34 AM
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My code is on a 2001 Civic LX 4cyl 5sp VTec ULEV

Glad I'm not the only one with this issue. I started having a power loss problem initially. When the car was cold (not during the winter, wasn't a freezing issue) it would have a complete power loss, but never stall. Pushing the clutch in and waiting a few seconds the rpms would return to normal and after starting to drive again it would sometimes continue to bog down a few more times. After five minutes or so it wouldn't happen again. During this issue the CEL never came on. Hoping it was a real bad batch of gas I ran the tank down to almost empty and filled again. The problem didn't stop at that point.

The car has sat for 2-3 months at a time for the past 2-3 years. The power loss problem seems to happen much less often now, but I got the P0420 code, after clearing it the last time it returned a P0420P almost immediately. We want to sell the car so I really don't want to just start throwing money at it without a better idea of the actual issue. I'm starting to lean toward changing the O2 sensors, starting with the one before the CAT. I was thinking that an O2 sensor could make sense and that as the exhaust heated up it began to function better. But I'm not sure if an O2 sensor could effect the power loss that much. I was of course told I needed a new Cat, but I'm going that route until I know for sure it's bad, that's 20% of the value of the car. Any additional help someone can offer would be greatly appreciated, thanks in advance.
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post #57 of 71 Old 08-31-2013, 01:18 PM
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I've got a 2000 accord with the vtec engine, 160k miles.

I started getting P0420 just before I had to bring it in to get it smogged in CA for it's registration. I erased it and it came back as soon as the monitor reset. I decided that if I were going to have to put a new CAT on it, I'd likely change the 02 sensor in the CAT anyway and start out fresh on everything. With that in mind I changed out the sensor first to see if it would solve the problem. No more codes and no more CEL and it easily passed smog.

I had replaced the front O2 sensor five years ago when I bought the car. It had front end damage which had crushed the wiring where it entered the sensor. I first tried a Bosch. No dice. It kept throwing a pre-heat code on the sensor. I read in several forums where Hondas can be pretty fussy about wanting only Honda OE O2 sensors installed in them. I returned the Bosch and bought the Honda sensor. BINGO! No more issues with it.

I did the same with the sensor this time- bought it from Honda. Honda is very proud of their O2 sensors as they cost over double of aftermarket ones but you know what? It's worth it to me to eliminate that one very important variable in the equation. Some of these issues are hard enough to diagnose as they are without trying to determine if the brand new part you just put on is the issue itself.
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post #58 of 71 Old 08-31-2013, 02:48 PM
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To troubleshoot further you will need to see some data from the car using an ODBII Bluetooth adapter and a Smartphone, tablet or a laptop to look into the issue further. Here is a relatively inexpensive one ($13.59) at newegg



Then you just need a program on your phone or laptop, I have an Nexus 7 and this works great

Android Torque Pro $4.95

The P0420 code just says that the CAT efficiency is below threshold, but it is not as simple as just replacing the CAT. It just means you have to look into the issue further to determine the exact cause. Is there another code set at the same time? If so that may be the cause of the P0420 also. If you have other codes fix those issues, clear the codes and start the engine. Warm the engine until the water temperature is stable. Then, increase engine speed for about three minutes, usually between 2,500 and 3,000 rpm; this will help the catalytic converter light off. After this, look at the wave forms between the front and rear O2 sensors. If the front O2 wave form is switching from high to low (rich to lean) and the rear is close to a straight line, the original converter should be OK. If the rear O2 sensor is mimicking the front one, the converter most likely took damage and may need to be replaced.


Possible PO420 code causes

The following engine related problems are known to generate the PO420 code:
◾Intake manifold air leaks
◾Fuel injector problems (leaks)
◾Incorrect spark plugs
◾Ignition timing
◾EGR problem
◾Defective catalytic converter
◾Oil or antifreeze entering exhaust
◾O2 sensor not operating correctly
◾Road damage to converter
◾Silicone contamination

Most, if not all, catalytic converter failures are caused by a problem or malfunction somewhere in the emission system ahead of the converter. So, it’s very important to determine what actually caused the converter to fail, so that the problem can be repaired and a recurrence can be prevented.

Current Honda vehicles
2010 Acura RDX Turbo AWD/Tech 67k miles - Daily Driver
2013 Accord EX-L I4 Auto 53k miles Black Pearl - Wife's car
2005 Acura TSX Auto 208k miles - Youngest Daughter
2013 FIT Sport Auto - 24k miles - Oldest Daughters car
Former Honda Vehicles
2001 Acura MDX Totaled t223k
1991 Accord LX auto sold 185k miles
1995 GSR sold miles
1991 Civic SI Crushed by a tree during a tornado 1997
1989 Prelude SI soldr miles
1986 Civic 5 speed sold miles
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post #59 of 71 Old 08-31-2013, 03:04 PM
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BTW the Rear O2 sensor is what the computer uses to determine if the Cat is below efficiency. If the computer sees the sensor after the CAT go from rich (over 600mV) to lean (under 300mV) it will set the P0420 code or if it sees no data (or set a P0430 code for bank 2 on V engine). If the Fuel ratio is correct the CAT will keep the rear sensor flat.

The front O2 sensor is used by the computer to keep the air/fuel ratio correct. You should also look at the long term and short term fuel Trim on these cars and make sure it is close to 0 % anything above 8% indicates an issue, it has to go to 20% before the computer sets a code.

Current Honda vehicles
2010 Acura RDX Turbo AWD/Tech 67k miles - Daily Driver
2013 Accord EX-L I4 Auto 53k miles Black Pearl - Wife's car
2005 Acura TSX Auto 208k miles - Youngest Daughter
2013 FIT Sport Auto - 24k miles - Oldest Daughters car
Former Honda Vehicles
2001 Acura MDX Totaled t223k
1991 Accord LX auto sold 185k miles
1995 GSR sold miles
1991 Civic SI Crushed by a tree during a tornado 1997
1989 Prelude SI soldr miles
1986 Civic 5 speed sold miles
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post #60 of 71 Old 05-20-2014, 11:47 PM
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Have a 2004 honda accord replaced both o2sensors and now have replaced the cat three times. The check engine light still comes back on... What should I

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