Check engine light goes on and then off every 1000-2000 miles.

My 05 Tacoma has 250,090 miles, well maintained....but my check engine light comes on and then goes off again every 1000-2000 miles. It shows an emissions code for my Cat Converter. However my father has an 05 Tundra 150,000 + miles that does the same thing. A mechanic told him that the check engine light comes on like that as a reminder to check old O2 sensors and cat convertor in older year Toyota Trucks, then the light will go off again. He said that this doesn't mean there is a problem with these parts.

Have any of you experienced this? Is there any truth to this mechanic's explanation?

 

Sounds like nonsense to me

 

Also it runs fine when this code is read. And otherwise, no rough idling or anything like that.

 

So would you recommend getting the Cat Converter replaced even if it's running fine? Want to make sure I make the right move given how expensive new Cat Converters are.

 

That code pops up for me occasionally on my 01 Tacoma. Usually happens when I have a big altitude change. For example if I go camping up in the mountains for a day or 2, then start driving home, when I’m a couple thousand feet down the hill my O2 almost always trips. I’ve been told it’s because I live next to the beach and the sensor is having trouble readjusting.

In short, don’t worry about it, I don’t.

 

If your referring to the P0420/430 codes hat can happen when the converters start getting to the point where they are marginal and may pass the drive cycle one time and fail it the next or you can have a slight exhaust leak or O2 sensor that is getting flaky as well.
Converter codes will not cause any difference in driveability, only if the converters get restricted or plugged will driveability be affected but that is unrelated to any codes.

The bit abut it being a reminder is from the oldschool (70s-early 90s) early feedback/EFI systems that did have an emissions/O2 light that came on at mileage intervals as a reminder to check the emissions equipment.

 

It’s possible what you were told is true. Seeing how you’re asking about it, you probably don’t have a tremendous amount of trust with this shop.

This is more likely what’s going on.

Shops make money selling parts and labor. The more of each they sell, the more they make. This unfortunately can lead to dishonesty jibberish nonsense. Which in turn unfortunately leads to honest shops having to deal with customers who got burned previously.

Luckily these days we have things like yelp. You can browse through the reviews to see what others experience has been with a shop. Weed out the fake friends and family reviews and ones written by entitled people who will be unhappy no matter what happens.

 

What O2 code gets set? Have you checked for vacuum leaks? My thinking is driving down from the mountains would be extended periods of closed throttle time, the perfect conditions for a small vacuum leak to confuse a oxygen sensor.

 

I think PO420. It could be a vacuum leak, never really looked into it much. If it is a vacuum leak would it be a line coming off the throttle body perhaps? It usually goes away on its own after a week or so of driving back at sea level