wphamren

Gossgary, appeciate the response. I will read the link you provided, and see what I can do to find the fault. I'm not worried about anything more than keeping my Subaru going in the best way it can. I will say, your expalnation is well received. I'm posting here because I'm not convinced by what the dealer told me, and the internet is FULL of reasons why the P0420 code is potentially so much more than the cat. I guess my best course is to go back to why this happened after the HG repair- starting with how it was reassembled. Thanks.

John, appreciate the insight. Legacy is at 117000. It has not been my primary dirver until recently, so, it has not had much use the past couple years. I did have the exhaust manifold gaskets replaced during HG job. Dealer did not do job, but very reputable Subaru service place did. I will be doing the work myself on exhaust; I would have done HG if I had more time. I see the point of replacing the O2 sensors first, and cheking for exhaust leaks, but doesn't a catalytic converter effiiency check determine that? That was the understanding I was given of the test. This was done at a Subaru dealer.

I thank everyone who responded with the check first, but the catalytic efficiency check is done on the dealer computer to confirm/check if it is sensors or the cat. It's the cat. I still am wondering if the sensors need to be replaced when replacing the cat?

A month ago, I finished a head gasket repair and other much needed maintenance on my 2000 Legacy. I then got the P0420 code from CEL; there are no other codes. I went through all the online troubleshooting techniques with no success, so, I took it to my local dealer to do a catalytic converter efficiency test. They told me my cat is bad, but both sensors are O.K ( I trust it). So, can I just replace the cat, or do I need to replace the sensors because it will be a new cat? It will be a BOSAL cat, if that matters.

I have a 2000 Legacy with Whiteline suspension upgrades, lowering the car 1". I just got done doing inner tie-rod boots and ball joints, and I took it today to a tire shop to get an alignment. I was told that my front camber is not adjustable, but I seem to remeber that it was. They left it -.04 LF and -1.5 RF. I beleive the rear is not, and it is -1.7 LR and -2.6 RR. I'd like to know how I might fix this, and how immediate should I fix it. If needed, the caster is 3.2LF and 3.1RF. Toe is .02 all around. Thanks.