Sending it back is a good decision. You don’t want to add an unknown to the diagnostic problem. The advice above is good: just drive as normal, fill up at your normal place, and hope for the best. I expect though that light will come back on. You do have quite a few miles on the car after all. Cats don’t last forever. But you can address that problem if/when it occurs.
If I had this problem on a car with pre- and post- cat O2 sensors (which neither of my cars has), I’d get out the lab scope and see what the two sensor’s signals were doing. The way it works, the computer monitors those two signals, and if they look too much alike, it thinks the cat isn’t doing anything, so it flags the P0420 code. But a person can look at those signals with a lab scope and do the same thing. It might be obvious what the problem is just by looking.
I feel setting up a lab scope is more trouble than I want to go though. How many car owners have lab scopes? George, how much did you pay for your lab scope?
I prefer using the common method of monitoring and comparing oxygen sensor values on a scan tools graph screen, of course you’ll have to ask your mechanic to diagnose this as most people don’t own professional scan tools ether.
The lab scope was a new diagnostic scan tool feature in the 1990’s but very few techs that I worked with would use it. In the late 90’s communication rates between the PCM and scan tool became 100 times faster, you can now set up lab scope type graphs on the scan tool via the OBDII connection.
Yeah, I must admit I am curious about what exact part triggered the code. I am fairly handy when it comes to certain things, but definitely not what you would call a shade-tree mechanic or anything like that, so… probably best to leave the diagnostics to an expert.
Years ago I had friends who were handy with this kind of thing. Makes me think I should go out there and make some new friends (you know, ones that have really awesome tools in their shop like lab scopes). LOL.
I feel setting up a lab scope is more trouble than I want to go though. How many car owners have lab scopes? George, how much did you pay for your lab scope?
$50, used. I’m not suggesting the OP do it that way. That’s up to the OP. I was explaining what I’d do in that same situation. Everyone has uniquely different skills and tools at their disposal. My dad used to always tell me: There’s more than one way to skin a cat.
I am pretty sure the O2 sensors are the originals. When I bought the car (at 144,000), the CarFax report said it had only had one owner, and although a few of the original service records came through on CarFax, it was far from complete. So, I’m just guessing, no, probably not.
Sooooo… stupid question here. Seeing as how it’s been more than 15,000 since I bought the car, I guess it’s time for a new air filter? (please, no K&N jokes. Already sent the darned thing back to California).
I replace the engine air filter in my Corolla every 15-20,000 miles. This isn’t a particularly dusty area, so it still looks pretty clean when I do the job. In a more dusty area, driving on dirt roads, etc – I’d replace it more often.
Speaking of how dust and sand affects the air filter change interval …
Years ago I drove my truck across northern Arizona, Yuba I think is the name of the town I passed through. It was summer and very hot and windy and thick clouds of sand was blowing everywhere. It was a pretty good sized sandstorm. About midway across the state the engine started to act weird, so I had a look at the air filter and it and the housing was full of sand. I cleaned it out the best I could there by the side of the road which fixed the engine problem. So I continued where I was going. But when I arrived at my destination it was night, and I realized I could barely see through the windshield b/c of glare from the oncoming car’s headlights. Turned out the sandstorm had pitted the windshield so badly I had to have it replaced just from that drive.
For years my commute involved a stretch of highway that had a lot of dumptrucks on it. There was no reasonable alternative
And at the time, they were not required to tarp their loads, so the wind would blow debris onto EVERYBODY’S windshields. Even if you sped up to quickly pass them, some debris always got onto your windshield. And the next truck would be just ahead, anyways.
Over time, it became really hard to see out of the windshield, particularly if it was bright outside
Ive used K&N filters for many many years…on many many engines, they work just fine. Whats the problem with a K&N? Doubtful you will see any performance advantage in that vehicle, however you can benefit from the re useability of that filter…you never need to buy a new one now etc… Ive found that they make a considerable difference in a motorcycles ability to breathe, so thats a good thing when youre after more power on a cycle. I also like to be able to wash re oil and re use the filter itself. Ive never seen a downside to them actually.
K & N are reusable. The problem is they contaminate the MAF sensor with oil residue. I had one in my Camry for the first 50k miles. It started idling funny. MAF had a brownish oily film on it. Cleaned it and the problems were gone. I never had this happen to any of my Toyos except for my 09 with the K&N. Now I only use standard air filters.
Ive used K&N filters for many many years…on many many engines, they work just fine. Whats the problem with a K&N? Doubtful you will see any performance advantage in that vehicle, however you can benefit from the re useability of that filter…you never need to buy a new one now etc… Ive found that they make a considerable difference in a motorcycles ability to breathe, so thats a good thing when youre after more power on a cycle. I also like to be able to wash re oil and re use the filter itself. Ive never seen a downside to them actually.
The downside is that they have the potential to create problems if they are not oiled or serviced properly (either too much or not enough) while offering no benefit. They don’t filter air any better nor do they provide added horsepower or fuel economy unless the car is driven at 100% throttle.
Motorcycle engines are of no comparison to a modern day car engine.
The downside is that they have the potential to create problems if they are not oiled or serviced properly (either too much or not enough) while offering no benefit.
The other problem is they let more air in…thus unfiltered air. Unfiltered air equates to more dirt.
@MikeInNH
"The other problem is they let more air in…thus unfiltered air. Unfiltered air equates to more dirt."
Huh? Think about that. It could be true. I’m no engineer, but can immediately think of a situation that negates that. CSA
(you know, ones that have really awesome tools in their shop like lab scopes). LOL.