Subaru Outback Forums banner

1881 - 1900 of 1907 Posts

·
Registered
2005 Impreza Outback Sport 2.5L, na, MT5, "Sue Bee"
Joined
·
46 Posts
What brand of injector cleaner did you use? If you look through this thread or search on 'Seafoam', you will see several times where Cardoc has recommended it. It can be added to the gas tank (one can per tank full) and/or drip fed into the intake manifold using one of the vacuum fittings. I had the P0420 coming up persistently (even after new plugs, wires and new fuel injectors, etc.). I was beginning to think it was finally time to replace the cat but tried the Seafoam in the tank and the light has stayed off for around 1,000 miles now. If you have a laptop computer you can also do some in-depth diagnosis using the free Romraider software. You can log all of the engine sensors while driving and then open the saved file in Excel and plot various parameters (many examples in this thread) that can take much of the guesswork out of diagnosing this code.
Thank you @MikeC5 !
I have not tried Seafoam in this car but used it in my 1967 Mustang to clean out carbonization with some success.
The fuel injector cleaner I used was "Lucas brand 'Upper Cylinder Lubricant, Fuel Injector Cleaner and Fuel Conditioner' ". I put in about a quart (I know, too much, I must have been impatient). I usually put in a lot less than that. Never had a problem with it even on my highly finicky Mercedes.
The CEL P0420 did not come on until after I ran it about 500 miles and filled it up a couple of times. When I put in the additive it was at a full tank. Then I got the CEL P0420 at a half tank. Thinking there might be bad gas, I filled it back up with 93 octane premium and have reset the code a couple of times while changing/testing other (cheaper) things...but it always comes back after 60-70 miles of driving. The tank is still at 1/2 full. This car gets great mileage.
I'll have to go for a long drive somewhere tomorrow to use up the remaining half tank with the remaining Lucas additive.
I'd like to download this Romraider software and will look up where it is (I'm sure there's info on a thread here somewhere).
 

·
Registered
Joined
·
16,836 Posts
I'd like to download this Romraider software and will look up where it is (I'm sure there's info on a thread here somewhere).

Requires a computer or laptop (for portability) with Windows or Linux, and an OBD adapter cable; many use a Vag-Com KKL 401.9 cable that's readily available on Amazon or eBay at a reasonable cost (in the $20 range). Check the listing to make sure it say the unit uses an FTD232 chip, as these have been found to work better.

In addition to downloading and installing the program, two downloadable files are required to be saved, and the program instructed to access them when operating. I'm fairly sure there are posts in this thread about setting up, but if not, and you get started and need help, post and someone will help out.

@traildogck -- do you have links to your threads on setting up?
 

·
Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
Joined
·
16,009 Posts
@plain OM

Thanks for the prompt. I would suggest following the RomRaider FAQ and "getting started" offerings.

http://www.romraider.com/index.php/Documentation/RomRaiderFAQ

All the links are there for everything you need for tuning/reading/flashing. For regular logging only the above cable is adequate.

But in addition here are my threads for dummies.




They are old threads eh?
 

·
Registered
2005 Impreza Outback Sport 2.5L, na, MT5, "Sue Bee"
Joined
·
46 Posts
@plain OM

Thanks for the prompt. I would suggest following the RomRaider FAQ and "getting started" offerings.

http://www.romraider.com/index.php/Documentation/RomRaiderFAQ

All the links are there for everything you need for tuning/reading/flashing. For regular logging only the above cable is adequate.

But in addition here are my threads for dummies.




They are old threads eh?
Wow! Thank you! I am saving this offline. I won't have a chance to look at Romraider until after the holiday but I'm sure your information will help a lot!
Thanks again! :D
 

·
Registered
Joined
·
1 Posts
Hey everyone, I have a '15 Forester XT (not an Outback, I know, sorry) with the dreaded P0420 code. Troubleshooting it is a little beyond my skill, but I did buy a code reader and took pictures of the data stream for both O2 sensors in hopes someone here might be able to guess what's up.

I bought the car just over a week ago, and the dealership filled it up with regular gas. My hope is that the issue is simply that, however I can't be too sure.

Symptoms:
  • P0420 code
  • CEL on, Hill Assist light on, cruise control disabled, S mode
  • even at running temp the exhaust seems steamy, but I might just be overthinking it
  • poor gas mileage (avg. 20 on highway, 16 in city)
Other than the above the car runs great. No stuttering, it accelerates smoothly, etc.

Images of the O2 sensor reads below.

Idling, with 1 instance where I revved the engine just a bit:
475118


After clearing the DTC:
475119


I have zero idea what a "normal" or "healthy" data stream would look like, so forgive me if nothing stands out. I'm hoping someone here can really just tell me if I should be alarmed by anything here, or if the data stream won't tell me anything and I need to keep troubleshooting.

Thank you!
 

·
Registered
Joined
·
2 Posts
There are several reasons a P0420 will come up as an error and illuminate the MIL. A lot of people are scared of it. They get all excited and search all over the internet to try and guess at what they should do. Reading good advise and bad trying to save money and hoping its not a Catalytic converter gone bad.

Well, I have been trying to inform as many people as I can that the 420 code is not a scary animal that is going to eat your wallet. This code simply means that somewhere in the chain of events that controls the overall performance of the engine there is a problem and you have to find it.

List of possibilities:

Fuel quality (low quality fuel a/k/a Murphy Gas)
Fuel quantity (filter or pump issue)
ignition issues (plugs, wires, coils injector flow)
temperature control (too high or too low)
vacuum leaks
exhaust leaks (not only an annoying noise, but it effects proper value reporting to the ECM by the AF and O2 sensors)
poor amperage conductivity (i.e. battery or cabling)

Sensor issues can be:

MAF (Mass Air Flow Meter)
MAP (Manifold Absolute Pressure)
ECT (Engine Coolant Temperature)
AF (Air/Fuel ratio a.k.a. Front O2 which can be a single bank 1 for 4 cyl or bank 1 or bank 2 H6)
O2 (This is the actual O2 behind the CAT that lets the computer know how the CAT is functioning)

So, in an attempt to show some data and explain simply what I found, I decided to video some diag segments and show the live data from the vehicle. I will do this to show differences as they come up. Today I had 2 Subarus with emission issues. The first was a 96 Legacy wagon AWD 2.2 that was low on coolant due to a crack in the radiator and the ECT value was causing issue with starting because it controls the IAC position. It reported high temperature to the ECM which closed the IAC. No air - No start. The second is the following.

I am uploading video now. It is from a 2001 LLBean with just shy of 199,000 miles. The MIL was on for a week and went off this morning as the owner was driving it to me. I checked all the systems on the car for error codes and the only one was a P0420 still stored as active. So I began watching data from the car.

I first let it sit for a couple hours to cool down. Checked the oil, dirty but full. Coolant level was good. Battery amperage checked out excellent at 705 A output and conductivity measured 650 A at the block so grounding was good. Air filter was mediocre so I left it for now to keep the car in the same condition it was in when the MIL set. The owner hadn't driven it much since the light, so the same gas was in the tank.

There is a point in the video where I thought one thing and said another. I referred to the oxygen sensor as storing oxygen when in fact I meant the sensor was reflecting the cat storing oxygen then it let go, the cat. There still may be an issue with the cat, but at this time I cannot condemn a part that is working through another issue with the engine.

In this case, the engine is overheating due to a stuck thermostat and the HC's are actually being burned due to overheating before reaching the CAT. Since this is occurring and the ECM is programmed to expect other values from the O2 sensor, it reports that the CAT is not functioning as it was designed and illuminates the MIL. So a thermostat is in order as well as a fuel filter which you will see why toward the end in the fuel trim value for bank 2. Since the engine runs almost perfect up to the point of overtemp, there is no need to replace the ignition plugs at this time. It was recommended based on the mileage as preventive maintenance. The owner is considering selling the vehicle since she doesn't drive it much anymore and has a smaller car she uses for the higher MPG's, so the car is parked until she decides to repair it or its sold.

2001 Subaru Outback LLBean P0420 Diag - YouTube

You also need to know that if any of the above issues go on too long, it will damage the catalytic converter to the point it will necessitate replacement.
I will check into the parts and things that you have listed thank you
 

·
Registered
08 Outback LL Bean H6 - 236,000 miles
Joined
·
14 Posts
I created my own post for issues, and was told that it would be better to migrate over to this one. Here is a link to my previous post. I have a 2008 Subaru Outback H6 with 236,000 miles. Essentially, I have had an increasingly common, and now constant P0420 code, accompanied by bad gas mileage, engine misfiring, and other codes including p0026, and electrical codes such as c0071 and 0045. Cardoc said that it could be a bad battery or accompanying cables. I believe my battery is fine, but have not checked the cables themselves. What is the best way to check if your battery is still good? And I will look the cables over later today when I am done with schooling. Thank you guys for any insight you may add to the situation.
 

·
Registered
2005 Impreza Outback Sport 2.5L, na, MT5, "Sue Bee"
Joined
·
46 Posts
How to check if your battery is good

Generally If there are multiple codes, troubleshoot the others first then the P0420 last. Sometimes addressing the others also solves the P0420. Keep us posted here what you find. 👍🏻
 

·
Registered
08 Outback LL Bean H6 - 236,000 miles
Joined
·
14 Posts
I went and bought a multimeter and tested the battery, its still good! And all of the cables looks good. As far as RomRaider goes, I am having trouble finding the right definitions and stuff for my specific car (08 Outback 3.0 L.L.Bean). Where exactly can I locate them? Sorry, I don't want to download the wrong thing and mess something up. And I've been to the GitHub, but had no luck finding the right file. Once I get RomRaider set up, I am going to check the Engine Coolant Temperature sensor resistance while the engine warms up, because I have read that it going bad could cause some of the issues I am experiencing, such as it running rich and causing my bad MPG, as well as the misfiring.
 

·
Registered
Joined
·
16,836 Posts
@Subie_Gal I was still drafting when the above post was added. I add some additional details.

I am having trouble finding the right definitions and stuff for my specific car (08 Outback 3.0 L.L.Bean). Where exactly can I locate them?
For basic monitoring and logging, it's not necessary to find a specific definition file.

On the Romraider download page, there's links to two definition files that are needed; the Logger definitions and the ECU definitions.
You are required to download and install these definitions in order for RomRaider to be completely functional. You can find the latest ECU definitions HERE, the latest Logger definitions HERE and the Cars definition for the Dyno tab HERE.
(The Cars definition file is are optional. They are needed only for dynamometer display; if they aren't saved and available when the logger is opened, a pop up will ask to get them but closing that dialog will continue the Logger boot up.)

The Logger definitions links will bring you to a forum thread. The latest file is found at the bottom of the first post in that thread (currently logger_v346.zip). Download it, unzip, and save the resulting files in a folder on the computer (e.g. Romraider definitions). Similarly, the latest ECU file is found at the bottom of the first post in the ECU-linked forum thread. Again, unzip and store in the same folder.

Then, open Romraider. It will probably open initially in the Editor. There's a drop down menu at the upper left to open the Logger. (If the intent is primarily logging, then perhaps a shortcut icon can be set up on your computer to go directly to the logger).

While in the Editor, click on ECU Definitions at the upper left. The drop down menu will have ECU Definitions Manager. Click on that. A small window will appear. Click on Add, and find the ECU definition file folder that had been set up earlier. Select the ECU xml definition file to use, save, and done.

Next, open the Logger, click on Settings at the upper left, select Logger Definition Location, and in the popup, locate the Logger definition files that were saved earlier. Select the Logger xml file to use (there are language and metric/Imp options), then Open and it should be done.

The Logger will display a long list of engine and transmission parameters; these are all the possibilities in the Logger file. However, when Romraider actually connects to the ECM (or TCM), only those parameter available from the ECM/TCM will be displayed. Parameters to log can then be check marked. The data will be displayed to the right.
 

·
Registered
2006 Outback 2.5 na
Joined
·
42 Posts
If you will read through this thread, you will see that the code does not necessarily indicate a bad catalytic converter. A converter will go to crap if an issue is not corrected in time. Even when a bad cat is replaced, you have to identify what damaged it in order to keep from damaging the new cat.

As a reminder, and since this thread is so large, things that cause the code are vacuum leaks, (hose cracked, purge valve stuck open, gasket(s) leaking, loose oil fill cap, etc.; any unmetered air), bad battery, bad grounding, weak alternator, PCV valve clogged, slow reacting or bad AF or O2 sensors, type of fuel in the car, poor fuel delivery, leaking injector, misfire or poor ignition from a spark plug or coil, harness issues, oil condition and level, AVLS operation, knocking due to carbon build up or low octane fuels, torque converter problems, dragging brakes or bearings, exhaust leaks, timing belt alignment due to stretched belt or bad tensioner and engine temperature control.

Logging data and posting it up is the best way for us to help determine what the issue is. Any logger that lets you see the engine data PIDs and record and save as a CSV or spreadsheet is sufficient. Most use Rom Raider, others have used TorquePro and similar.

The cataclean is not going to make a cat work. It may clean out some of the carbon build up, but as far as making it work again, no. Once the metals in the cat deteriorate to the point of inactivity, it's done.
A bearing could cause p0420? hmmm
 

·
Registered
Joined
·
271 Posts
data logging is key, I had a sensor go bad on my car passenger downstream o2 sensor, it works fine and then all of a sudden it just goes bonkers. Waiting for replacement sensors (2 of them) and I am going to change out both of them.
 

·
Registered
2002 Outback
Joined
·
628 Posts
My P0420 has returned and is staying on steady now (Seafoam isn't helping any longer). It looks like the converter lights off when under higher load but under normal cruising the rear O2 sensor begins to oscillate. I also see the knock correction sometimes getting down to -10 degrees at some part throttle conditions. I noticed a few spikes in the warmed up idle RPM trace that look suspicious. This file also shows battery voltage dropping to just above 13 V momentarily. I have cleaned up the engine compartment grounds not long ago. Maybe it's time to replace the converter... If you have time Cardoc, I would much appreciate you taking a look to see if I missed something. I changed the attachment to a .txt file. If you copy it and then change extension to zip, maybe it will work.
 

Attachments

·
Registered
2005 Subaru Outback 2.5i A/T
Joined
·
32 Posts
Time to throw my hat in the ring...

The Car:
  • 2005 Subaru Outback 2.5i Base SOHC CA-Spec (U5)
  • 199,956 miles (tomorrow is the day I hit 200!)
  • Phoenix, AZ car its whole life, dealer serviced exclusively by original owner, now my OCD self services it. The converter heat shield nuts and bolt don't even show a lick of corrosion.
  • 'Top Tier' gasoline is always used in this car if that's worth anything, I don't know.
The Problem:
  • P0420 popped on in the middle of a 11,000 mile road trip this July.
Observations:
  • P0420 cycles on and off with an emphasis on turning off in city driving and on while cruising on the highway. I drove the car exclusively in the city for a week and light stayed off, I got on the highway recently and knew it would pop on quickly. It did, the code is extremely predictable after 6 months of living with it.
  • My gas mileage is fantastic and the car runs smooth as can be.
  • My car has 3 converters and 5 sensors that consist of 2 primary A/F sensors, 2 post primary cat oxygen sensors and 1 post secondary cat oxygen sensor.
  • The cats are OEM Subaru and the sensors are the OEM Denso units. I looked through all of the dealer paperwork of which I have from the dealer and original owner and the sensors or cats have never been replaced so these are original with 200k on them.
Before I go into my steps, here's a diagram that has helped my visual learning self: @plain OM knows I love my diagrams from my fuel tank/vent valve issue he and @aero901 helped me with last year. You'll notice my convention B1S1 = Bank 1 Sensor 1, so on so forth. From here on forward, I'll be referring to each sensor by BxSx FYI.



My Diagnosis thus far:
  • First, I plugged my AL319 into the OBD port and read the live data on the 5 sensors. There's a ton of fluctuation on all sensors in the city obviously so I got on the highway and went nice and steady at 70 mph. I noticed:
    • B1S1 = consistant at 2.7v
    • B2S1 = consistant at 2.7v
    • B1S2 = consistant at .750v
    • B1S3 = consistant at .350v
    • B2S2 = going BONKERS all over the map from .050v - .950v
  • Second, I checked the readings at warmed up idle and the readings are more or less the same as above. 4 sensors very consistent, an B2S2 just fluctuating all over that 0-1v range.
  • Third, I crawled under the car with an IR thermo gun and took some readings off of the 2 primary cats under the heat shields in the identical spots on both units. These readings were taken at a warmed up idle, I did not have anyone on hand to hold a higher RPM.
    • Bank 1 primary cat read 567* front, 587* back
    • Bank 2 primary cat read 542* front, 550* back
  • Fourth, tomorrow I plan on swapping B1S2 and B2S2 since they are the same sensor part number from Subaru/Denso. I want to see if the live data will then show either one of the following:
    • B2S2 still going bonkers, or;
    • B1S2 is now going bonkers.
Ideally the above sensor swap will tell me if the sensor is whacked out or if Bank 2's primary converter is roached. I'll say a handful of hail marys that it's the sensor, I'm unemployed and those converters are not in anyones budget. I also have emissions due next month, go figure. Ironically, the car being CA-spec has helped tremendously with diagnosis and having another side to compare to.

data logging is key, I had a sensor go bad on my car passenger downstream o2 sensor, it works fine and then all of a sudden it just goes bonkers. Waiting for replacement sensors (2 of them) and I am going to change out both of them.
This is exactly what I have going on. @YeuEmMaiMai anything to report back on your sensor swap?
 

·
Registered
Joined
·
271 Posts
sensor replacement 100% resolved the problem. Driver side had aftermarket and passenger side was still OEM. both were replaced with DENSO parts (Subaru OEM)
 

·
Registered
2005 Subaru Outback 2.5i A/T
Joined
·
32 Posts
sensor replacement 100% resolved the problem. Driver side had aftermarket and passenger side was still OEM. both were replaced with DENSO parts (Subaru OEM)
Thank you for the confirmation!

Okay, so today turned into being a lot more involved than it needed to be. If you look 2 posts up you will see that my game plan for today was to swap sensors B1S2 and B2S2 since they are the same part number to see if I get erratic voltage readings from my other cat. I pulled B1S2 without issue but (I'm assuming) the idiots at the dealership cross-threaded B2S2 when they replaced the engine at 115k. I wasn't too worried about the sensor itself since it was the one giving me crazy voltage readings yesterday, I was more concerned about the bung. I tried to hand screw my other known good sensor (B1S2) into the bung and it wouldn't go. Lisle makes a tool (part number 12230) that you should order today for your box. I couldn't believe I didn't have one, but for $6, its made in the USA and a LIFESAVER.

I chased the threads and we were back in business. I was able to hand thread in my known good sensor into B2S2, but since I did not have a good sensor (Amazon has not arrived yet......), I put a drain plug into the other bung to cap it off and prevent it from sounding like an old Deere. I am SO happy to report that I am now getting a consistent .750v from B2S2 with my known good sensor that was in B1S2 yesterday. I'm really hoping that once the new sensor arrives and I put it in B1S2, we are fixed up and the P0420 is a thing of the past.

For the money, I'd prefer to replace both of these post primary cat sensors, however due to being unemployed, it's mission critical purchases only.
 

·
Registered
2005 Impreza Outback Sport 2.5L, na, MT5, "Sue Bee"
Joined
·
46 Posts
Hi everyone. I wanted to give you the resolution to my P0420 problem! I want to thank everyone who helped me, offered advice, or who left advice for problems in the past that I was able to read here, and learn from.
After a two-month extensive diagnostic process, consulting the experts here, reading up on various technical guides, as well as consulting with two separate mechanics (who I've done business with many times, and trust). Over the 2 months, I investigated every system in the car, fixing what popped up needing to be fixed. Cataclean and acetone didn't help this time. Sensors tested OK, catalytic converter did not. I got a Walker cat (from RockAuto) at the recommendation of my mechanic, and he replaced the existing cat -- which was not OEM -- and that could explain why it failed. I also replaced the flanges, spring bolts, etc. See the attached pics for what I ordered and part numbers in case that's helpful for anyone.
That fixed it! Code has not come back and I've already put on another 200 miles. Got the car inspected, which is good for 2 years.
Car runs great; had it in heavy traffic today in north Jersey and this 15-year old auction rescue not only kept up, but handily avoided a couple of stupid drivers doing boneheaded things!
 

Attachments

·
Registered
Joined
·
21 Posts

Requires a computer or laptop (for portability) with Windows or Linux, and an OBD adapter cable; many use a Vag-Com KKL 401.9 cable that's readily available on Amazon or eBay at a reasonable cost (in the $20 range). Check the listing to make sure it say the unit uses an FTD232 chip, as these have been found to work better.

In addition to downloading and installing the program, two downloadable files are required to be saved, and the program instructed to access them when operating. I'm fairly sure there are posts in this thread about setting up, but if not, and you get started and need help, post and someone will help out.

@traildogck -- do you have links to your threads on setting up?

Requires a computer or laptop (for portability) with Windows or Linux, and an OBD adapter cable; many use a Vag-Com KKL 401.9 cable that's readily available on Amazon or eBay at a reasonable cost (in the $20 range). Check the listing to make sure it say the unit uses an FTD232 chip, as these have been found to work better.

In addition to downloading and installing the program, two downloadable files are required to be saved, and the program instructed to access them when operating. I'm fairly sure there are posts in this thread about setting up, but if not, and you get started and need help, post and someone will help out.

@traildogck -- do you have links to your threads on setting up?

Will this cable work? Amazon.com: VIMVIP VAG-COM KKL 409.1 OBD2 USB Cable Auto Scanner Scan Tool Compatible with Audi VW SEAT Volkswagen: Automotive
 
1881 - 1900 of 1907 Posts
Top