jbk

Last night our "check engine" light went on with the code P0420 on our 1999 Forester (127k miles). An independent mechanic checked it out this morning and says the two O2 sensors are fine, so he's recommending replacing the catalytic converter. He's also recommending replacing the O2 sensors. The total cost would be around $1150. He did say that it's not urgent and that I can probably wait until the next smog test.

1) According to a little printout from Autozone (I borrowed the engine code reader from them), P0420 could be caused by other things. My mechanic seems pretty confident the catalytic converter is the problem. Is it worth getting a second opinion for $50-60?

2) Is there a way to do this cheaper? I see posts by people saying I can get a universal catalytic converter put in for half the price. Is this possible in California? Are there any drawbacks to this? Can this be a DIY job if I get right kit? (I don't want to do any welding myself).

I'll call some muffler shops when I get off work but I thought I'd ask here while I'm at work......

Thanks.

 

2.5x_sleeper

Sounds a bit high to me! I had a high flow replacement CAT installed in MY03 by a trusted muffler shop for $200. I'm very picky, so I watched the entire installation & it was "perfect".
You could get a rear O2 sensor for $100 or less & install it yourself. The rear sensor is pretty easy to replace. Unless you weld & have the tools to size the pipe, the CAT is not DIY!

The rear O2 sensor only monitors the efficiency of the CAT & doesn't affect the engine operation. If your Forester is running poorly, there could be a problem up stream (A/F.. air/fuel, front O2 sensor, this sensor is critical) & that could be overwhelming the CAT so it's letting too much O2 pass thru & this is being detected by the rear O2 sensor... CEL code P0420...

A thought... how about addressing the rear O2 sensor first? If that corrects the problem, you're only out the cost of sensor. If it doesn't correct the problem, you were going to replace the CAT & the rear O2 sensor, so you're still not out anymore than you were going to be...

Bobby...

__________________
'07 FSXT WRB AT - COBB dyno Protune - Stage 1
'03 X PBP AT +AVO turbo kit! (son's)
'95 Neon Sport

bbottomley

What's your model year and mileage? There's a federally mandated 8/80 warranty on the cat! I know.

__________________
2003 XS Premium MT >160k miles! ● 2005 Impreza 2.5 RS MT ● Robin-Subaru Powered Generator

jbk

1999 Forester with 127k miles, so I think I'm SOL.

BobD

If you go for an after market cat converter, make darn sure the heat shields on it are like the original. The converter is just under and close to the passenger side rubber CV boot, so if you save money with an after market product that skimps on the heat shield, you'll get problems that will offset the savings.

Let us know what you find and prices. I recently replaced both O2 sensors and now have the same code myself at 173K miles.

Apparently, the logic looks at the differential O2 and if they are close, the computer assumes the cat converter is at fault since the downstream O2 should be lower once the unburned hydrocarbons get oxidized.

pleiad7

Also check out this very informative thread on the P0420 code: P0420 - Catalytic Converter Efficiency Below Threshold

__________________
-Silke
04 FXT PP PSM ~ "Subed"
98 Forester S ~ "Slynki"

TSTRBOY2004

it could be if you find one that someone removed to put in an after-market system....

RedImpreza07

Hell a Factory Subaru cat is around $600 sesnor is $125 take 1 hour to do the job. I did it my self. so $725-$1150 = $425 labor that foolish labor costs.

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2008 Forester X Premium 5MT Garnet Red Pearl

taekwondome

I have the same problem on my Forester 2000. My mechanic quoted me a price of around 1,200 to 1,500. In other states you can get a Catalytic convertor for about $200.00. Only in California are the prices so sky high due to Federal requirement for the catalytic convertors used on cars in the state.

pleiad7

Get one off ebay: SUBARU Forester 2.5L 1999 2000 2001 Catalytic Converter:eBay Motors (item 350193277965 end time May-21-09 13:35:02 PDT)

We were going to do this for our 98 that needed a new cat, but our shop saved the day at the last minute with a used one they sold us at scrap metal price.

__________________
-Silke
04 FXT PP PSM ~ "Subed"
98 Forester S ~ "Slynki"

jkoppee

when my '01 had the 420 code I replaced the rear O2 sensor and didn't see the code again for quite some time at which point I then threw a universal cat on and all was well. I would say shoot for replacing the rear O2 first, if I remember correctly it was the cheapest part, and see if your troubles go away. Usually you can replace it yourself.

2.5x_sleeper

You might want to check this thread $5 fix

BTW, welcome to the forum!

Bobby...

__________________
'07 FSXT WRB AT - COBB dyno Protune - Stage 1
'03 X PBP AT +AVO turbo kit! (son's)
'95 Neon Sport

AlleyCat

May be you need to give it the ol' Cale Yarborough run on the highway to burn off all that crap on the Pt/Pd/Rh. Wide open throttle 3rd and 4th gear, 3500-5000 rpm run ups for at least 30 seconds. Sounds shorter than it is.

taekwondome

Bobby, thanks for the link. However, my 2000 Forester has over 160k miles on it so I'm not sure if this is the fix. I noticed that on the $5 thread the car in question had roughly about 18k miles on it. Any advice?

Rick

pleiad7

At that mileage your cat likely needs replacement. California is tricky now... you have to use an OEM cat (pricey!) or one of the few aftermarket cats that are CARB-approved, if I remember correctly. If the aftermarket cat doesn't have the required number stamped on it, most all muffler shops will refuse to weld them into your exhaust because they can be fined a pretty hefty sum.

__________________
-Silke
04 FXT PP PSM ~ "Subed"
98 Forester S ~ "Slynki"