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2005 Outback 5spd
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Discussion Starter · #1 ·
Hey all, first time poster here, hope you can help me out.

For a few weeks my 05 Outback has been developing an increasingly annoying rattle when driving. Thinking it was just the heat shield, I ignored it. However, one day completely at random my car seemingly lost at least half its power, and sounds extremely muffled and clogged. Revs ok, but it is very slow and struggles on any sort of incline, with the metallic rattling being very noticeable. After banging on the cat a few times and getting a similar noise to the rattle when the car is at speed, I self diagnosed it as a bad cat, confirmed by a local shop. The shop heard me out but didn't examine the car, they seemed very confident the cat is the culprit. My only reservations in this diagnostic are that the check engine light is not on, which doesn't seem to be inline with the usual PO420 exhaust system errors.

If it is indeed the cat, how reliable are aftermarket cats? Found a Walker for $280, seems reasonable I am just concerned about how aftermarket vs OEM will hold up.

Any help is much appreciated, and advice in DIY would be quite helpful as well.


On the Super Mod Squad
2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
28,372 Posts
a shop typically wants to change things out as they buy,...sell for profit, and install things to make money.

vs. say looking for a possible exhaust heat shield making the noise, and using some dollar store bailing wire to stop it.


miles on the car?

cats rarely go bad, without plenty of codes and loss of oil or coolant through them before that.

Premium Member
(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
19,599 Posts
the noise on banging may be confirmation, but vacuum gauge testing can sometimes show exhaust blockage.

you might consider that the knock sensor is bad I guess....?
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