subegrl Posted July 20, 2007 Share Posted July 20, 2007 I will need a new catalytic converter, I'm pretty sure. I have 171,000 miles on the car. Does anyone have an after-market catalytic converter they recommend? Quote Link to comment Share on other sites More sharing options...
PAezb Posted July 20, 2007 Share Posted July 20, 2007 I will need a new catalytic converter, I'm pretty sure. I have 171,000 miles on the car. Does anyone have an after-market catalytic converter they recommend? I dont know, but aftermarket probably not much cheaper than purchasing OEM from a Subaru Internet discounter like 1stsubarupart.com, subarupartforyou.com, or Jason at Mike Scarff Subaru in Auburn, WA (1-866-528-5282) Are you sure you need a new CAT, and not just an O2 sensor (forward O2 sensor in most cases)? Quote Link to comment Share on other sites More sharing options...
subegrl Posted July 20, 2007 Author Share Posted July 20, 2007 Well, I will replace the 02 sensors as well. The car has started bucking intermittently. I replaced the knock sensor and fuel filter, and reset the ecu, and ran some fuel injector cleaner in it, all in the past six months. I am going to take it to my mechanic on Monday, but if he says that it needs a cat he doesn't do that kind of work. Quote Link to comment Share on other sites More sharing options...
PAezb Posted July 20, 2007 Share Posted July 20, 2007 I believe the CATs come with new O2 sensors (at least I think Subaru OEMs do) so you have nothing to lose by replacing the O2 sensor itself ($60 to $70 part versus $500-$600 for a CAT replacement). They are fairly easy to replace too. I seen several instances (including my sister with a 96 Legacy) where they were told they needed a new CAT (do to a CEL) and the problem was resolved by replacing the forward O2 sensor. Do you have any CEL codes? Just want to make sure you don't start spending big bucks when it *may* be a lesser problem. Subaru CATs usually last a long, long time. Quote Link to comment Share on other sites More sharing options...
subegrl Posted July 20, 2007 Author Share Posted July 20, 2007 That's a good point. I could just replace the 02 sensors first. I have gotten the p0420 in the past but ironically it's not showing a code right now. Quote Link to comment Share on other sites More sharing options...
PAezb Posted July 20, 2007 Share Posted July 20, 2007 That's a good point. I could just replace the 02 sensors first. I have gotten the p0420 in the past but ironically it's not showing a code right now. Don't worry about the rear O2, just the forward one. That's the one the ECU relies on to make fuel/air adjustments. Quote Link to comment Share on other sites More sharing options...
subegrl Posted July 20, 2007 Author Share Posted July 20, 2007 Don't worry about the rear O2, just the forward one. That's the one the ECU relies on to make fuel/air adjustments. Thanks:) Quote Link to comment Share on other sites More sharing options...
subegrl Posted July 20, 2007 Author Share Posted July 20, 2007 Also, could this be a bad/dying fuel pump instead? The car runs great 98% of the time, but a couple of times now it has started this bucking. Fuel economy is still fine, engine temp is fine... Quote Link to comment Share on other sites More sharing options...
PAezb Posted July 20, 2007 Share Posted July 20, 2007 Possibly. Or maybe one of the other sensors like the MAF, engine coolant sensor, etc. But the P0420 indicates from the O2/CAT area, but any one or combination of the 3 sensors listed above are major suspects that can throw that code. http://www.obd-codes.com/trouble_codes/generic/p0420-catalyst-efficiency-below-threshold-bank-1.php I'm sure some others will chime in here soon who had the same symptoms with their Subies. Quote Link to comment Share on other sites More sharing options...
subegrl Posted July 20, 2007 Author Share Posted July 20, 2007 Well, even though there's no code I plugged in my Car Chip sensor this morning (had it out for no particular reason so back in it goes) and I will read what it says tonight, it may be helpful it may not. Quote Link to comment Share on other sites More sharing options...
ron917 Posted July 20, 2007 Share Posted July 20, 2007 For P0420 codes, read this: http://www.troublecodes.net/articles/catfailure/ Quote Link to comment Share on other sites More sharing options...
PAezb Posted July 20, 2007 Share Posted July 20, 2007 For P0420 codes, read this:http://www.troublecodes.net/articles/catfailure/ Excellent article! Quote Link to comment Share on other sites More sharing options...
subegrl Posted July 20, 2007 Author Share Posted July 20, 2007 Well, I just had to take the car down to the bank to deposit a check, and it ran fine. The intermittent nature of the problem really is making me think (hope?) that it is a sensor of some kind. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted July 20, 2007 Share Posted July 20, 2007 Well, I just had to take the car down to the bank to deposit a check, and it ran fine. The intermittent nature of the problem really is making me think (hope?) that it is a sensor of some kind. if you said , i missed it, what make , model , year, miles, trans....recent service? Quote Link to comment Share on other sites More sharing options...
subegrl Posted July 20, 2007 Author Share Posted July 20, 2007 if you said , i missed it, what make , model , year, miles, trans....recent service? 01 Forester, 171k miles, manual tranny, has had a new fuel filter and knock sensor in the last 5 months or so. Also I run Techron in my tank the same day I get my oil changed and I get my oil changed every 4k. Quote Link to comment Share on other sites More sharing options...
ferret Posted July 21, 2007 Share Posted July 21, 2007 AHHHH 01/02 Forester / Legacy / Outback. Does it buck after warmup like you have bad gas? ( water in the gas? ) If so, these were known for defective front O2 sensors. They would not set a code for this problem. But after warming up they intermittently sent a signal to the ECU that the engine was running rich. The ECU shut down the injectors. When there was NO exhaust, then the ECU turned on the injectors again. So the ECU is fooled and never sets a code !!! I have seen this quite a few times. To the point a guy couldn't restart his 02 Outback and it was flat bedded to the dealer. When it came off the truck, guess what .... it started and there was no bucking. 2nd time that happened, he left the car at the dealer. Quote Link to comment Share on other sites More sharing options...
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