Error Code 0420
11-21-07, 08:06 PM
#1
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Error Code 0420
The dealer replaced my pan and rear main gaskets. A few days later I get the check engine light and 0420 code. Bank 1 cat, or after cat O2 problem. Dealer says I need a new after cat O2 sensor. Do you think this is my problem? I want to change it myself. Is Denso the one to get? If not, which brand is best, and where is the best price?
The wire goes thru the floor pan and must plug in inside the cabin. Are there any tricks to getting to the plug inside the cabin,
like getting under the driver's seat and carpet?
What and where is the best deal on cats?
Any and all advice will be much appreciated.
Thank you.
bankr
The wire goes thru the floor pan and must plug in inside the cabin. Are there any tricks to getting to the plug inside the cabin,
like getting under the driver's seat and carpet?What and where is the best deal on cats?
Any and all advice will be much appreciated.
Thank you.
bankr
11-21-07, 08:21 PM
#2
There are 3 things that could be wrong with that code. 1.Gas leakage on exhaust system 2. Heated oxygen sensor 3.Three-way catalytic converter.
How many miles do you have on your car as at least the last 2 should be covered for maybe 75 to 90K.
How many miles do you have on your car as at least the last 2 should be covered for maybe 75 to 90K.
11-21-07, 08:54 PM
#4
Super Moderator
BCP43002 hit on the head 
The gas leakage is a little rarer but still can occur.
P0420 is a low catalytic converter efficiency, very common for vehicles where I live due to the gas quality and elevation, but more of a cat than sensor issue here where I am at.
The dealer should have checked the resistance on that O2 sensor to verify it was on the fritz, not just take the code and say it was this or that. I would stick with the Denso brand (knowing some people in my RX300 forum who have gotten other brands instead).
I would ask in the LS400 forum about the cat for your vehicle as aftermarket cats are a cheaper option such as those from Magnaflow. (I am on my second aftermarket cat myself). Not sure if the area you live in is subject to emissions testing.
The gas leakage is a little rarer but still can occur.
P0420 is a low catalytic converter efficiency, very common for vehicles where I live due to the gas quality and elevation, but more of a cat than sensor issue here where I am at.
The dealer should have checked the resistance on that O2 sensor to verify it was on the fritz, not just take the code and say it was this or that. I would stick with the Denso brand (knowing some people in my RX300 forum who have gotten other brands instead).
I would ask in the LS400 forum about the cat for your vehicle as aftermarket cats are a cheaper option such as those from Magnaflow. (I am on my second aftermarket cat myself). Not sure if the area you live in is subject to emissions testing.
11-22-07, 09:38 PM
#6
This is how Dealerships make their money!!!!
Take it to a trusted mechanic first! Have him inspect the car, and ask him if there's anything wrong. If not, wait until the engine light goes off, and then make your judgment.
My brother went to get his oil changed just like you, and the engine light kept going off. His personal mechanic told him that dealerships, and other mechanics tend to trick the computer into thinking something is wrong with the car when it actually isn't! Be careful =]
Take it to a trusted mechanic first! Have him inspect the car, and ask him if there's anything wrong. If not, wait until the engine light goes off, and then make your judgment.
My brother went to get his oil changed just like you, and the engine light kept going off. His personal mechanic told him that dealerships, and other mechanics tend to trick the computer into thinking something is wrong with the car when it actually isn't! Be careful =]
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