Forester 2001 L - Stock
101k Miles
P0420 - Catalytic Converter Efficiency Below Threshold
The forester has been throwing this code for a few months now, typically shows up on long highway runs (but to be fair, that is the vast majority of my driving). I bought a scanner from scantool.net, which I am quite impressed with for $60 new. This is the only code that's been thrown, so I am assuming it's the cat, I just want to gather what insight I can before going through with the repair.
I have seen some posts saying it could be the rear O2 sensor failing. How likely is this, given it has not thrown its own code? I have called around the area, but nobody here can do an exhaust check to find out for sure. I've also heard that an emissions check might not give any useful information, since the efficiency code is thrown well before the problem gets out of hand.
Assuming it is the cat, is there a good way to determine if it is just the front or rear unit, and replace individually? Also, can anyone offer any insight on the best replacement unit? I saw TexasForester's excellent writeup on the Eastern #40237 and his issues with that unit. Does anyone have any experience with other possibilities?
Any help is appreciated... Thanks!
101k Miles
P0420 - Catalytic Converter Efficiency Below Threshold
The forester has been throwing this code for a few months now, typically shows up on long highway runs (but to be fair, that is the vast majority of my driving). I bought a scanner from scantool.net, which I am quite impressed with for $60 new. This is the only code that's been thrown, so I am assuming it's the cat, I just want to gather what insight I can before going through with the repair.
I have seen some posts saying it could be the rear O2 sensor failing. How likely is this, given it has not thrown its own code? I have called around the area, but nobody here can do an exhaust check to find out for sure. I've also heard that an emissions check might not give any useful information, since the efficiency code is thrown well before the problem gets out of hand.
Assuming it is the cat, is there a good way to determine if it is just the front or rear unit, and replace individually? Also, can anyone offer any insight on the best replacement unit? I saw TexasForester's excellent writeup on the Eastern #40237 and his issues with that unit. Does anyone have any experience with other possibilities?
Any help is appreciated... Thanks!
► Administrator's note - you might also be interested in this thread:
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$5 fix (merged thread)
Hi, I have been searching in vain for an explanation of the $5 fix (mechanical) for the PO420 code that I have seen references to. Would someone be kind enough to point me in the right direction to it please? Thankswww.subaruforester.org