I have a 2002 Camry - V6 1MZ-FE engine 120000 miles, original owner
Check engine light came on, car running fine (of course).
OBD Codes posted:
P0430 Catalyst Efficiency Below Normal (Bank 2)

P0420 Catalyst Efficiency Below Normal (Bank 1)

It appears to me that the OBD codes are saying that 2 of the 3 Catalytic Converters failed simultaneously
This does not seem possible unless I got some bad gas

 

Could be bad gas. Did you fill up prior to the CEL coming on?

Were any repairs done on the car prior to these faults?

Suggest using the gas up and refilling the tank, then clearing the codes and determine if they return.

 

Did have some repairs done but they were completed several weeks before the failure. I normally do the minor stuff, oil, brakes etc. but I had a leak that turned into 2 problems, bad power steering line and valve cover gaskets. My mechanic is as honest as they come, he knew I was thinking about trading and suggested that I just clean it up and trade it in.
Wife filled it up a few days before the CEL came on for me at Costco. I'm sure their gas is ok but I normally fill at Quicktrip where they seem to move a lot of gas.
My mechanic is good but he doesn't work on Toyotas everyday.
He's convinced that it's the Cat(s) nothing more.
I had it fixed because several friends asked about buying it for their kids.
It's never been in an accident and it's in great shape interior & exterior.

If it is gas, are there any gas treatments that might help?
My co-worker suggested Seafoam.

 

I suggest not using Seafoam for this issue.

Unfortunately the engine computer does not directly test the converters. It uses A/F or O2 sensors to monitor exhaust gases before and after the converter. The signal of the sensor after the converter should be different from the sensor before. If not, the computer thinks the converter is bad and sets a code.

If only one code had been reported (meaning one failed converter) I would be much more confident it was a converter. Typically a failed converter code means a failed converter.

However two converters failing at the same time seems odd thus might look for a common issue causing these codes rather then assuming both converters have failed together. Converter replacement is also very costly another motive to fully check other causes.

The following can cause these codes to appear:

Failed or lazy 02/AF sensor (a common failure). A sensor failure should generate its own code but this is not 100%.

Leak in exhaust manifold or exhaust system before the converters. There are no codes for exhaust leaks. Extra air in the exhaust will cause the sensors signals to be different then the norm.

Failed coolant temp sensor for the engines computer. It has its own code but not 100%.

A fluke, meaning clear the codes and wait to determine if they reappear.

You typically are not going to damage anything even if the both converters have failed, but of course will not pass a smog test. There is time to troubleshoot or wait to determine if the codes once cleared reappear.

A Toyota dealer or someone with a real time ODBII scan tool can view real time data of the sensors as the engine is running and compare it to Toyota data available in the service manual. If all the sensors check out OK along with the finding no exhaust leaks this would add more evidence it was both converters.

 

Joey P
Thanks so much for the help, I drove the car around all morning resetting the CEL time and time again. I decided that I was getting too old to run the Camry around to get the proper diagnosis and my trusty mechanic was maybe out of his league on this one.
I traded the old girl this afternoon with the CEL burning.
I figure it cost me about 2k on the trade.
Again, thank you and all the guys out there that really know their stuff and are willing to take the time to share it...

Don S in St. Louis

 

FYI, I just had the 420 code on a 2000 Lexus Rx300. Long story short one or both of the warm up catalytic converters disingrated and clogged the rear catalytic converter. I replaced all three converters CEL off with no problems.

Brandon

 

Thanks Brandon, If I would have kept it I think the only thing to do if you plan on keeping the car awhile is to replace all of them.
Probably should just replace the entire exhaust system.
Did you replace any of the sensors too?
What'd it end up costing you?

 

I think it was about $680 to replace all three converters. I did not replace any sensors, but I may have to because the CEL is on again.

Brandon