Just replaced and fixed related codes for air/fuel sensor on 2000 Camry 4 cylinder. No CEL for 2 days and today...bing CEL. Code coming up now is P0420.

First question is will this prevent the car from passing a state (Maryland) emmissions test? And 2) If I clear the codes and drive for a day (a number of on/off cycles and say 10-15 miles), will a standard emissions facility have enough data to run diagnostics ? Assuming CEL doesn't come back on.

 

is the CEL didn't get back probably it will work.

 

Did you only replace the Bank 1, Sensor 1, sensor?

What brand, part number etc of sensor was installed?

Suggest an internet search on your states emissions test requirements, most states have a web page on the specifics of the test.

If the check light is on the car will fail the test.

One issue with clearing codes is this will wipe the computers memory and it will need to go through all the self checks again. Most states tap into the ODBII system to determine if all readiness checks are complete meaning the computer has run all self tests and all are complete with not issues. These test have various driving parameters such as MPH, time, etc and may take a good deal of driving time.

If too many checks are not complete (say 2) the car will not be tested, the tester may state to come back in a few days to allow the checks to be completed.

 

I only replaced the one and only a/f sensor which did clear codes P1130, P1135, P1133, P0125. I knew that theres a potential problem with using an aftermarket a/f so given my Calif emissions 4 cyl, I purchased the a/f straight from my Toyota shop.


Last fall I had midas replace the entire exhaust system from engine all the way back....could this code me coming from an exhaust system leak? Midas guaranteed this replacement exhaust system would pass any inspection test........


R,

 

All things being equal the P0420 code is typically a bad converter. However a failing sensor located after the Cat could cause problems (this is rare) along with an exhaust leak ahead of the senor that is behind the Cat. The leak need not be large.

The computer compares front and back sensor output readings, if the same readings this is an indication the Cat is not working properly. The readings should be different if the Cat is working because the Cat changes the exhaust gas makeup.

If Midas replaced the Cat, check your warranty. If a bad Cat and still under warranty take the car to them and complain

 

Attached is a diagram of my Camry's exhaust system....Midas told me that I needed parts 16288 (converter), 2 gaskets (31374), 48319 and 21328 w/ gasket).

So, they excluded the 555xx piece...would that be the section where the downstream sensor would be? If so, I wonder if the converter will resolve the issue???? would I get a 0420 error code if there was a leak/leaks in the 48319 or 21328 parts?

Thanks,

 

Also, in addition to my above question, if I replace the converter do I also need to get a gasket where the converter meets the engine block? Looks like a metal gasket from under the hood but I'm not seeing anything online to suggest if I replace the converter that I'll need anything other than a gasket between the converter and the pipe that meets it (gasket 31374 per the diagram in the my above post).

I removed the heat shield from the cvonverter and it look sfine to me...no pitting or hiles that I can see. I did discover several exhaust leaks downstream aft of the catalytic converter to muffler and tailpipe....is is reasonable tothink the 0420 code is because I've got leaks well downstream after all the sensors???

 

16288 is 1 converter. The can at the end of the 555XX pipe may be a second for a total of 2 converters (2 used on California emissions cars).

If the leaks are down stream of the No 2 converter and any 02 sensor on the exhaust pipe then most likely would not cause issues.

Check if the car has three 02 - A/F sensors on the exhaust system.

The first converter bolts to the head with the metal gasket which you should replace.

What kind of warranty did Midas have on the No 1 converter. If still covered by warranty take it back to them.

 

Toyomoho: roger roger on the metal gasket on converter one where it bolts to engine.

Of interest, Midas' estimate and recommendation was for converter 1 and all pieces after converter 2, so they can to the conclusion that the section between converter 1 and 2 was okay. as mentioned, I took the heat shield off of converter 1 and the pipes actually appear to be in good exterior shape....I was sort of expecting to see deterioration or a leak in converter one, but I can't see anything.....I was thinking to start with replacing everything after converter 2 because of the leaks I found to see if that would clear the code, but if this won't solve the 0420 problem which I think is what you are saying, I might be better off starting with replacing converter 1 and then follow with parts (after converter 2) over the next month or two(????) Thoughts to logic?

Also, converter 1 just looks to be a bit of a tangle of pipes coming together at the bottom of the unit....the a/f sensor plus into it. because the 0420 code is highlighting a below threshold error would the code only exist based on a leak or is there some other sort of interior issue that could have occurred in converter 1?

Thanks

 

All other things being in good working order the code means the converter performance has dropped below at set level. Converter do wear out. Other factors causing premature failure are excessive engine oil burning, engine coolant leaks into the exhaust, excessive rich or lean mixture.

Since the check system for the converter is indirect a problem with a sensor or exhaust leak can cause the check system to trip this code when the converter is not the problem. If everything is correct and working OK, the code is indicating correctly that the converter is bad.

The original converters typically came with a 80K/8 year warranty. After market converters typically have shorter lives but should last longer then a year. Check for a Midas warranty.