2005 Outback Check Engine Light

[ninerashbourne]

Hello Everyone,

   I'm an owner of a 2005 Outback LL Bean and yesterday while driving my Check Engine Light came on and also my Cruise indicator is flashing on and off. I was able to obtain a trouble code, P0420. Can anyone tell me what this code means ? The car has 105,000 miles on it and this is the first time the

Check Engine light has come on.

 

Sincerely

Ninerashbourne

[Legacy777]

I moved your post to the new gen forum.

 

P0420 is related to the rear O2 sensor and catalyst inefficiency. These codes can sometimes pop up for random reasons. I'd recommend taking it to an auto parts store that will check/verify the code and reset the ECU. If the code comes back, your rear O2 sensor could be bad or something to do with the wiring.

[montana tom]

I agree with legacy about clearing your codes to see if they come back. Sadly every time your check engine light comes on ... your cruise control light will flash and the cruise control will not work until you clear the codes!  A Subaru (BETTER) idea that they should have never have thought of !  Purchasing a cheap code scanner will allow you to read the codes and to clear them yourself. 

[1 Lucky Texan]

don't let anyone sell you a cat converter unless there is UNEQUIVOCAL evidence it's bad. That code is a nightmare and many people suffer with solving it because there are many reasons it can be set; exhaust leaks, poor combustion,corroded grounds, rodent-chewed wires, bad battery/charging conditions, etc.

Edited May 30, 2015 by 1 Lucky Texan

[brus brother]

don't let anyone sell you a cat converter unless there is UNEQUIVOCAL evidence it's bad. That code is a nightmare and many people suffer with solving it because there are many reasons it can be set; exhaust leaks, poor combustion,corroded grounds, rodent-chewed wires, bad battery/charging conditions, etc.

I hadn't heard of the bad battery/charging conditions...

I am up against this P0420 right now with a pending emissions inspection.

For the past five years I have been able to clear the code and set the systems to pass emissions but now  after I erase the codes, the computer throws another P0420 even before the systems are set.

This 05 MY has 3 cats and 5 O2 sensors. Now who thought that was necessary??

[ninerashbourne]

Thank you everyone for your input. Here is were I'm at the moment with this problem. I purchased some SeaFoam to clean the Injectors as about a week before the Check came on my wife who drives the car, ignored the low fuel indicator and ran out of gas.I was hoping that perhaps the injectors were causing the problem. I then brought the car to an Auto Service Center I have been going to for over 10 years and they have quoted me @ $1,500 to replace the right bank Cat and two sensors. Needless to say that quote nearly gave me heart failure. So from reading the forums out there I decided to replace the Air/Fuel Sensor & O2 Sensor on the right bank ( which is the bank they're telling me is the problem, 3 Cats on this car ) The on board system was reset and I was told to drive the car for approx 100 miles and hopefully the system would remain clear. However 68 miles into it the Check Engine came back on,by the way the above work has cost me $577 so far. I also have a pending emissions test. I am at a loss now as to what to do. Looks like I'm going to have to bite the bullet and get the new Cat. Will hold off for a week or so. If anyone has any further input I would be very grateful to hear it.

 

Sincerely

Ninerashbourne

[1 Lucky Texan]

might be worth spending $100 for an opinion from another shop.

 

right away I have concerns when someone says "you need a cat and 2 sensors to clear P0420"

 

it's almost impossible for those 3 items to all be bad simultaneously. Someone is troubleshooting by the 'law of averages' - change enough stuff and you might catch the bad part. That approach might be forgivable if I do it myself - may still be cheaper using my own labor plus, I'm at least getting some new parts. But, when you are PAYING for labor from a supposed-pro , it's inexcuseable. There are voltage and oscilloscope tests for the sensors and propane and thermal tests for the cat conv available to PROPERLY trained and equipped mechanics.

 

If you elect to go forward with all these new parts, be sure to ask the shop what their next move is if the code comes back inn a few weeks, or can they guarantee they are fixing the problem.

Edited June 1, 2015 by 1 Lucky Texan

[Caboobaroo]

The the 2004 and 2005 Cal-spec emission cars, the P0420 is a nightmare. This is three cat, 5 oxygen sensor system.

 

Had one in recently that I put a new B1S1 oxygen sensor in to see if it would help (this is after another shop did an cheap B1 cat) and within a couple weeks, it was back with a P0420. By the time I was done (over 3 different visits), the car had all three cats and all 5 sensors replaced.

 

Don't cheap out on the cats if you do need to replace one. I would start by checking the 02 sensor reading to see if you have a lazy sensor. Basically a sensor that isn't sending the ECU info fast enough.

[idosubaru]

the P0420 code is a debacle.  there's no good way to diagnose it - technically speaking you should do a thorough analysis - but no one really does this unfortunately, cardoc is the rare person who can thoroughly diagnosis it, but this would be ideal to find someone who can do this:

http://www.subaruoutback.org/forums/66-problems-maintenance/49537-p0420-diagnosis.html

 

If an underlying issue caused the converter to fail then it's going to cause the new converter to fail, because converters generally can, and are designed too, last the life of the vehicle. 

Like this:

http://www.subaruoutback.org/forums/66-problems-maintenance/24353-catalytic-converter.html

 

generally converters are a process of elimination - address other things first and end up there as a last resort.  what I would do:

1. repair any exhaust leaks

2.  what's your gas mileage - the car should be running well/tuned up - bad gas mileage indicates a performance issue maybe eroding the converter efficacy over time

3.  replace O2 sensors first - fronts then rears

 

 

I plan on owning a car 250,000 miles or more and don't expect the O2 sensors to perform 100% for that long - so I generally preemptively replace them around 150k or so anyway so i can get another 100,000 miles out of them.   rather than limp along slow and lazy sensors or wait for issues or replace them when i'm unlikely to own the car much longer.  that's my excuse in my head for replacing O2 sensors that makes me feel better abuot it anyway.  gonna have to do it sometime - might as well do it all now.

Edited June 3, 2015 by grossgary

[brus brother]

yup. I have the 2005 cal spec 3 cat/5sensor mess. 150,000 miles now but started with the p0420 around 105K miles.

For the past 4 years I had been able to reset the ecm and pass inspection BUT now I can't seem to get the systems to read as ready before a new p0420 pops up.

I worked with cardoc (cited above by grossgary) a year ago and at that time after MANY scanned runs and resets, he diagnosed that the B1 cat was toast.

Today I ordered a $250 Eastern Catalytic converter (5yr/50K mile warranty) bank 1 for the car and will report back. If it gets me through inspection and another 2 years down the road, I'll feel like the money was well spent. Can't see throwing $1500+ into this car when the results can be so iffy even with SOA parts.

The front sensor had been replaced already and the Bosch tech advised that a lazy rear sensor would have only worked in my favor.

Alls I know is what I read on the internet or heard on Roller Derby... and what cardoc told me!

Fingers crossed.

Edited June 4, 2015 by brus brother

[brus brother]

http://www.easterncatalytic.com/education/tech-tips/the-misleading-nature-of-the-po42o-code/

There's a lot of good reading on the P0420 on the above link.

Eastern Catalytic sells cats but the info concerns proper diagnostic steps and other sections deal with preventive measures for healthy cats.

[brus brother]

Update:
1. Received Cat from Eastern today BUT

2. Managed to clear the code and get all systems to read as ready and passed emissions testing SO

3. I am now the proud owner of a cat that won't be needed for at least two years until emissions testing rolls around again.

Sorry but I won't be able to contribute more to the discussion for now.

UPDATE: Called AutoAnything.com and they sold me a return label for $10 AND no restocking fee! Can't beat that for service and I don't need to store the cat on the off chance that I will need it in the next 2 years before inspection rolls around again.

Edited June 5, 2015 by brus brother