My check engine light went on, but has since gone off. The cose read "PO420" which is "Catalyst System Efficiency Below Threshold". Other than changing the catalytic converter, any suggestion as to remedy this? I have an 04 Outback Sedan Ltd. with 61,000 miles. Thanks.
R....
If you Google 'Subaru P0420' you'll find lots of info on the subject. If it's intermittant, it could be nothing or maybe one of the O2 sensors. If the cat needs to be replaced, which seems unlikely at 61k miles, it should be covered under the emissions warranty.
Dan D '99 Impreza 2.5 RS (son's) Central NJ USA
Don is right about the 02 sensor but keep an eye on the code, the warranty for the cat expires at 80K, after that it is big bucks that you'll have to pay. In a way I'm hoping for you that it is the cat, I'd much rather replace the $60 02 sensor at 100k rather than the $600-800 cat
-- John
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