Join Date: Mar 2011
Location: Mid Hudson Valley, NY (USA)
Re: PO420/PO430 Catalytic converter replacement???
Wow, lots of code questions this week. A change in the weather, maybe? Seriously, gas blends change with the season, and you might be a victim of the wrong fuel for the conditions.
OK, so you logged two codes - Catalytic converters functioning below normal threshold on both sides (bank 1 & bank 2). I could be that you simultaneously lost both cats, but I'd sure want to know why!! If there is an underlying problem, like a coolant leak, you are likely to wipe out the new cats in time. It could be a bad tank of gas (or the wrong blend) with contamination that dulled either the cats or the sensors. Sometimes this is reversible with a few tanks of premium. It could also be an ECU issue, and the cats are just fine.
Did they scope the outputs of the lower sensors thru the OBD port, or manually at the sensor terminals? Does it show a normal waveform, just displaced in voltage? Way out of spec, or just slightly? Did they try a tailpipe sniffer to see if it is rich in unburned hydrocarbons? Did they try clearing the codes to see if they immediately come back, or stay out for a while? From what you report, I wouldn't know if you should be changing cats or sensors!
If the upper sensors were throwing codes, this could spell real danger for the engine. The lower sensors are merely tattle-tale tellers, designed to prompt you to fix something that is causing an increase in pollution. Change the cats immediately? I think that's a bit rash!
Will they guarantee in writing that this will fix the issue? You are looking at $2k, with a reasonable likelihood that you'll be back there again because they didn't take the time to figure it out.
Current: '15 Sienna Limited Premium (FWD), '14 Subaru Outback, '13 Honda CRV AWD.
Past: '08 Sienna LE (FWD), '02 Subaru Outback, '02 Honda Odyssey EX