Trouble Code PO 420

My truck through a code this weekend i cleared it. It is not a first time. It is a 01 4x4 v6 5speed it has a k&n filter and intake tube. I would like to know what it means the computer at the auto store said PO 420 Catalyst System Efficiency Below Threshold (Bank 1) what does this mean my truck likes to die when you are running down the road like 40 or above and push in the cluth and put it in nuetral and coast. Sometime it almost dies but picks it self back up what is this. Please reply with any suggestions and info

Hey I have noticed nobody has replied with any info. I really need some help i came up again today. The yota dealer here wont tell me an answer he said it could be some senser like the MAF of o2 senser or even a cat it only has 85000 miles on it could it be a cat. Please help I need some info or even some opions on what it would be. Before something major goes wrong.

Thanks, Steffan

[haireball]

there are many possiblities, O2, fuel filter, fuel pressure regulator, if O2 has been bad for a while the cat can be plugged too....it could be gas cap problem (if gas cap doesn't breathe correctly will throw code) could be throttle position sensor....def sensor related...ummmmm

sorry

what have you done so far?? What have you replaced?

Go to the tacoma factory manual page http://fsm.afraid.org/
about the ¼ way down
Diagnostics##Engine (2RZ?FE, 3RZ?FE)##Diagnostic Trouble Code Chart

it is saying MAP sensor, o2 sensor, gas leak on exhaust or cat.....something is causing your engine to dump too much gas

then there is a link on 420 that will show you how to diagnose the problem..the steps involved

Hey I have a K&N code the oil from the filter be causeing the MAP to read wrong. I need some help what do they mean by gas leak. Please help it only comes up every once in a while it only came up twice in the past few days before that it only came up every blue moon help me out how can i track this down where should i start first. Thank for the info post more please.




Steffan

[wisctaco04]

Clean the MAF with a PLASTIC SAFE electrical contact cleaner that can be bought at Radio Shack or Home Depot. Unplug the sensor and douse it. Do not touch the filament or you will need a new one. Install and away you go. Did you over oil the filter? You are among the numbers who have had problems with sensors from the K&N. If your MAF is that bad you should pull the TB and clean that too. Once you disconnect the drive wires and plugs there are 4 bolts that secure it. Do not disconnect the coolant lines. Replace the gasket too. You will see how it is not completely round like the TB and it causes a restriction. URDUSA has the round ones for pretty cheap.