P0420 Solved for now

[Kalamen]

Thanks for the replies. I am only getting the P2096 and the P0137 when I have the anti-foulers installed. When they are installed, I don't get the P0420 code. As soon as I take them out, I start getting the P2096 and P0137 codes. I will read up on the other posts, but toro168 seems to have had the exact problem as I am having, so I will probably give the diode a shot. I recently replaced the rear 02 sensor and experienced the same results. I am in Oregon and we don't have to go through inspections where I live, so I am not too concerned about that. Any ideas on how much an aftermarket CAT runs for a 2008 outback?

[cardoc]

08? See, knowing the year and models helps. Call your dealership and give them your VIN and check on the ECM update to correct a P0420 and a CAT recall. If you are under 80k, its covered under the emission warranty. Even if you are higher, you should be covered.

[RedGeminiPA]

Originally Posted by cardoc

08? See, knowing the year and models helps. Call your dealership and give them your VIN and check on the ECM update to correct a P0420 and a CAT recall. If you are under 80k, its covered under the emission warranty. Even if you are higher, you should be covered.

In his defense, he did say "I am having the exact same issue on my wife's 08 subaru outback." It was the post right before yours.

[Kalamen]

I tried going to the dealership first and they did install an update to the ECU. However, since the car has 86K on it, they said the cat was no longer under warranty. As another note, the CEL will typically only come on every a few hundred miles, so whatever fault it is sensing, it doesn't happen that often.

[signage]

I would contact SoA and complain to them, this is a known issue and you are not that far past the 80,000!

[cardoc]

I tend to speed read the post.

I'll look it up concerning the CAT. As for it being an intermittent code, thermostat, type of gas, PCV or faulty rear sensor. The CAT could be deteriorating slowly and it's unable to store oxygen to assist in re burning and converting the HCs.

[Fibber2]

This may be more than you want to read, but I thought some of you with P0420 issues might want to know more about it.

An Engineers Perspective on the P0420 Catalytic Efficiency code

[RedGeminiPA]

Mine finally popped up again last night after being out for almost a month since last clearing. I just pulled freeze frame data:

Fuel Sys 1 CL
Fuel Sys 2 CL
Calc Load (%) 22.4
ECT(ºF) 190
STFT B1 (%) -3.9
LTFT B1 (%) 9.4
STFT B2 (%) -3.9
LTFT B2 (%) 7.8
MAP(inHg) 18.3
Eng RPM 2105
Veh Speed (mph) 57

I should note: I was out of town over the weekend, and I got gas from a "Bob's Quick Mart" or something like that, but the light didn't pop up until I was nearing the end of that gas, a little before the low fuel light came on.

We don't have many choices around here for tier 1 gas. There's a Sunoco station about 5 miles away, but the rest around here is typically Sheetz (a huge monopoly of a station in my town), and they're known for using the cheapest gas they can buy.

[Kalamen]

Thanks for the link to the article. It was an interesting read. I will replace the thermostat since it doesn't cost much to give it a shot. The only other item besides the cat on your list is gas type. We typically only put 87 in there, although I know it calls for higher octane. Do you think that is the probable cause? Also, do you think an 02 sensor stimulator would eliminate the CEL from coming on, although obviously it would not solve the issue?

[Kalamen]

I talked to Subaru of America today, and they simply said that it is not under warranty anymore, even though I complained that it is a common problem, etc. The funny thing is that she stated they have an extended warranty of 150k for the cat in several states (California, New York and a few others) for the 2008 year, but since I live in Oregon and they didn't adopt the increased emission restrictions until 2009, I only get the 80k warranty.