Subaru Forester Owners Forum banner
1 - 20 of 23 Posts

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #1 · (Edited)
After a series of problems and repairs/replacements under the hood, all indications point to a bad catalytic converter. Both the dealership and my independent Subaru shop have given me the same diagnosis and quoted around $1200+ for parts and labor.

How hard is it to replace it/them yourself? Provided that I get an O2 sensor socket before I begin, can it be done in a day/weekend? I haven't done much work on the Forester, but I have rebuilt a motorcycle including the engine, so I suppose I'm not completely mechanically inept.

I may have to do it twice. I'm looking to first try cleaning it out in either a citric acid bath or soapy water bath. I'll reinstall it and test it.

If that doesn't work, I'd like to replace it myself. I'm in OR so a 49-state cat would work. The part is $950 so I figured I could save myself $300 by doing it on my own.

If I'm being stupid (i.e. there are two converters to buy, it's horrible to access yourself) then just let me know. I'd appreciate the input! Thanks.
 

·
Moderator
2004 Forester 4EAT
Joined
·
5,465 Posts
If you can deal with the rusted bolts, it's really pretty easy. It looks like the front cat is an integral part of the exhaust manifold. This is actually a pretty easy thing to remove. Plan on cutting off and replacing the 3 bolts holding it to the mid pipe. Also plan on having a few extra studs for where it mounts into the heads. Sometimes the nuts won't come off the stud, but instead the entire stud just comes out of the head. The only advice I will give is to be VERY careful when loosening the manifold nuts. You don't want to break one of those studs. Use lots of penetrating oil. And if you're really paranoid, run the motor just long enough to heat the aluminum of the head without heating the exhaust pipe too much. Then all of the studs will probably come out, but then you can just replace them.
 

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #3 ·
This may be a dumb question but it would appear that the front cat that the O2 sensors plug into is the only one that should be replaced. Is this a bad assumption?
 

·
Moderator
2004 Forester 4EAT
Joined
·
5,465 Posts
Depends on what your problem is. What makes you think you need a new cat?
 

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #5 ·
Long story short: P0420. Repeatedly. Had intermittent misfires for a while, Subaru checked and said valves and did the valves.

Misfires happened again and they said, no it's actually electrical. Needed a new battery and cables anyway so I had them do that.

Misfires again with a P0420 this time. Took it to an independent Subaru shop. They said maybe cat, but they wanted to check O2 sensors and mass airflow sensor first. They said front O2 and mass airflow were bad. I was close to timing belt service anyway so I had them basically replace the O2 sensors and do the 105,000 mile service including timing belt, water pump, oil filter, head gasket (needed it because of a leak), hoses, plugs, etc.

After car completed a drive cycle, P0420 is back and here to stay. Based on new sensors and basically new everything under the hood, I'm thinking it is the cat. Got that diagnosis from Subaru dealer and independent shop. Both quoted the same parts and labor.

Anything else I should check? (Serious question. No one wants to replace a cat.)
 

·
Administrator
2007 Forester Sports XT 4EAT
Joined
·
41,247 Posts

·
Premium Member
2015 Highlander AWD XLE 6AT
Joined
·
4,255 Posts
The catalytic converter is covered by an 8 yr / 80K mile Federal Emissions warranty. Is your car past either of those limits?

Regards,
Jim / crewzer
 

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #8 ·
The catalytic converter is covered by an 8 yr / 80K mile Federal Emissions warranty. Is your car past either of those limits?

Regards,
Jim / crewzer
Jim,

Sorry for the delayed response.

My car has 102,400 on it now, so unfortunately I'm past the limit there.

I also looked into the "mechanical" O2 sensor fix but it looks like those spacers aren't recommended on the newer (2005+) Foresters because the rear O2 sensor now affects fueling so the car tries to compensate for the bad reading.

A third party cat from RockAuto looks like my solution at this point.

Brett
 

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #9 ·
Have you looked on Rockauto.com to see what the going prices are? Not a recommendation, just showing the price range. You might also find a good muffler shop that could weld on a new CAT. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
I won't do a weld-in solution (just my preference), but I did check RockAuto and saw some decent reviews of the Eastern catalytic parts on here, so I'm just going to go that route.
 

·
Registered
2000 Ford Focus Wagon 5 speed manual
Joined
·
463 Posts
I bought a Walker from rockauto the other day. I haven't had the time to install it yet, but as said before, the only remotely difficult part is going to be loosening the fasteners/O2 sensors.
 

·
Registered
2012 Forester 4 speed auto
Joined
·
1,151 Posts
Loss of confidence

Reading this story makes me lose confidence in dealers and independent mechanics who cannot diagnosis the cause of an engine misfire. I admit diagnosing a misfire is no easy task. However, a good mechanic can do it without GUESSING! A simple compression test would have verified the valves need replacing, an osilioscope would have qualified the O2 sensors and MAF.

Have all these repairs eliminated the misfires? All these misfire are most likely the cause of your burned out catalytic converter. I don't know what the emission requirements are in Oregon. In California a smog test station could easily verify that the converter is bad. I like breathing clean air so I don't recommend the $5 fix. I would recommend you take the car to a muffler shop to inspect the exhaust system. The P0420 code could easily be a hole in an exhaust pipe. Also the shop might have experience testing converters. Some times a tap with a hammer will reveal the converter is burned out. Good luck!
 

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #12 ·
[...] Have all these repairs eliminated the misfires? All these misfire are most likely the cause of your burned out catalytic converter. I don't know what the emission requirements are in Oregon. In California a smog test station could easily verify that the converter is bad. I like breathing clean air so I don't recommend the $5 fix. I would recommend you take the car to a muffler shop to inspect the exhaust system. The P0420 code could easily be a hole in an exhaust pipe. Also the shop might have experience testing converters. Some times a tap with a hammer will reveal the converter is burned out. Good luck!
The independent shop has done a good job. Most of the work they did was prompted by me not wanting to pay to have the engine work done again in a month. The O2 sensor and mass airflow sensor that they did fixed the misfires. They, too, thought that the dealer's misdiagnosis and continued driving with intermittent misfires (however slight) caused the converter to go bad.

Essentially it is my fault for trusting that the dealer had fixed the issue. I ordered a new cat, gaskets, studs, nuts, and bolts yesterday. Should be able to attempt the install myself later this week or on the weekend.
 

·
Registered
2000 Ford Focus Wagon 5 speed manual
Joined
·
463 Posts
Well, I actually got all the bolts (I'm sure original from 03) to come off, but I'm pretty sure the car spent most of its life in NM and AZ. Anyways, the rear 02 sensor stripped threads coming out, and the new Walker cat I had bought didn't fit. The rear flange was rotated like 30 degress from where it should have been. FML.

So, I'm returning it and buying the Eastern, hopefully that one was manufactured correctly.
 

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #14 ·
Well, I actually got all the bolts (I'm sure original from 03) to come off, but I'm pretty sure the car spent most of its life in NM and AZ. Anyways, the rear 02 sensor stripped threads coming out, and the new Walker cat I had bought didn't fit. The rear flange was rotated like 30 degress from where it should have been. FML.

So, I'm returning it and buying the Eastern, hopefully that one was manufactured correctly.
My Eastern is supposed to get here today along with some gaskets. Should know by the weekend if it goes well. May post a how-to with photos or something.

Sent from AutoGuide.com App
 

·
Registered
2004 XT 5 MT
Joined
·
1,113 Posts
Reading this story makes me lose confidence in dealers and independent mechanics who cannot diagnosis the cause of an engine misfire. I admit diagnosing a misfire is no easy task. However, a good mechanic can do it without GUESSING! A simple compression test would have verified the valves need replacing, an osilioscope would have qualified the O2 sensors and MAF.

Have all these repairs eliminated the misfires? All these misfire are most likely the cause of your burned out catalytic converter. I don't know what the emission requirements are in Oregon. In California a smog test station could easily verify that the converter is bad. I like breathing clean air so I don't recommend the $5 fix. I would recommend you take the car to a muffler shop to inspect the exhaust system. The P0420 code could easily be a hole in an exhaust pipe. Also the shop might have experience testing converters. Some times a tap with a hammer will reveal the converter is burned out. Good luck!
^^^ Well said, to many people(mechanics) throw parts at the car simple tests could have ruled out some of these items by looking at waveforms of said parts on an oscilloscope. Heck a vacuum gauge could have helped diagnose the valve/compression issue.

Sounds like you are on the right track now. Establish a re pore with the independent shop that you trust and you are good to go. There is no shortage of good independent Subaru repair shops in portland/oregon.

Here is an example of how your 0420 should have went down by the dealer or independent:
 

·
Registered
2004 XT 5 MT
Joined
·
1,113 Posts
Long story short: P0420. Repeatedly. Had intermittent misfires for a while, Subaru checked and said valves and did the valves.

Misfires happened again and they said, no it's actually electrical. Needed a new battery and cables anyway so I had them do that.

Misfires again with a P0420 this time. Took it to an independent Subaru shop. They said maybe cat, but they wanted to check O2 sensors and mass airflow sensor first. They said front O2 and mass airflow were bad. I was close to timing belt service anyway so I had them basically replace the O2 sensors and do the 105,000 mile service including timing belt, water pump, oil filter, head gasket (needed it because of a leak), hoses, plugs, etc.

After car completed a drive cycle, P0420 is back and here to stay. Based on new sensors and basically new everything under the hood, I'm thinking it is the cat. Got that diagnosis from Subaru dealer and independent shop. Both quoted the same parts and labor.

Anything else I should check? (Serious question. No one wants to replace a cat.)
I would probably be talking to the dealer service manager about all the unessary work they performed on your dime? Not trying to get you fired up but it sounds like you got fleeced unfortunately and it might have been in good faith because they didn't do the proper test and thought they were right. Only reason to do valves is if compression and leak down and or vacuum testing fails. Hopefully your new cat will sort it out.
 

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #18 ·
I would probably be talking to the dealer service manager about all the unessary work they performed on your dime? Not trying to get you fired up but it sounds like you got fleeced unfortunately and it might have been in good faith because they didn't do the proper test and thought they were right. Only reason to do valves is if compression and leak down and or vacuum testing fails. Hopefully your new cat will sort it out.
Don't worry, I paid nothing for all the valve work. The dealer knew they messed up. The second misdiagnosis was my issue with them and my reason for going independent. The electrical issues I wanted to get sorted anyway so that was money well spent.

Only engine work I paid for was from the independent shop.

Sent from AutoGuide.com App
 

·
Registered
2006 2.5X LL Bean Automatic
Joined
·
83 Posts
Discussion Starter · #19 ·
So, today was the day.

Removed the "protective" plastic shield first. Unplugged the wiring harnesses for both O2 sensors next so that when I unbolted the cat, it could drop freely. 6 of the 9 main nuts for the converter, specifically the ones attaching it to the bottom of the engine block, came off pretty easily by hand. The 3 nuts holding the converter to the midpipe were really stuck. I needed to let a couple liberal helpings of PB Blaster sit for a while and then used a cheap pneumatic impact driver to get them off. Slipped the converter down and away from the car. I didn't removed the heat shields to transfer to the new part for now. I may get back in there and do it later, but I need to get the car into the DEQ first.

That was the hard part. My new part is an Eastern Catalytic direct fit. When I first looked at it next to the old one, I thought one of the flanges was at the wrong angle. However, when I actually went to reattach it, everything was really easy and fit perfectly. It came with only 2 out of 3 necessary gaskets, but I had ordered a set separately. It also came with studs for the section that connects to the midpipe. A little test fit and anti-seize and I was off to the races.

Anyway, reassembly was smooth and easy and the test drive went well. I'll listen more carefully for any noises tomorrow and then reset the CEL and see if I did the job right.
 

·
Registered
99 Forester L
Joined
·
93 Posts
I would be surprised if replacing the cat fixed the misfire. It should fix the P0420 code though.

My '99 had a terrible stuck ring in cylinder #4, got to the point where the dead cylinder was noticeable at highway speed. I was putting a quart of oil in every 500 miles. The spark plug was covered with char, the inside of the exhaust header was coated with oil, I never got a cat fault code.

BTW, I commend you for doing this (presumably) in a driveway on your back, with no welder. I have access to a shop with lifts, etc. and that's still a PIA job!
 
1 - 20 of 23 Posts
Top