Does anybody know what this engine code means????

My check engine light came on at 62000 miles in my 2004 tacoma v6 4x4. And i I Took it to a shop and they said this code popped up "P0420 catylist system efficiency below threshold bank 1 ?" Has someone ever had this exact problem with their truck and what did they do to fix it?


I already tried shaking both cats and i dont hear any rattle so idk what the problem could be it has such low millage...

 

Need a cat

 

The Toyota P0420 code is one of the biggest pains, and is quite common. Just because that code pops up, don't suddenly think you have to replace the catalytic converter. (though in the majority of cases, that is the end result) First you need to make sure that the pre-cat and post cat sensors are working properly, and are not clogged or dirty. There are a few products out there designed to clean your sensors. A scan tool that is able to display live data is essential to properly testing this. You want the pre-cat sensor to show a nice steady wave-form that progresses from around 100mV up to around 800mV. This should be reasonably steady. The post cat sensor should be reading a much lower wave form, with not too much variation from the 450mV base line. If either sensor is not showing what is expected, then you can take the chance of cleaning them, or replacing them. when it comes to the sensitivity of this code, I always recommend replacing the Toyota sensors with factory parts. Too many people seem to have reported issues with aftermarket sensors, but I will say most who get the Denso are quite happy with the results. If after cleaning and/or replacing the sensors, the P0420 code returns, then you will be looking at the need to replace the catalytic converter at this point.