Need help - check engine light code p0420

How difficult are the replacement 2 02 sensor on a 2.7L 4 cylinder ?

Should I get the denso ones ?

 

there is a ratio between the signal from the front o2 sensor, pre cat (the air fuel one) and the rear o2 sensor that is measured by the PCM/ECU and when it gets out of range the CEL is triggered. This ratio is used to determine if the cat is working as it should be. Bad, slow and none responsive o2 sensors can trigger this as well as oil consumption. A cheap cat is just that, a cheap cat. they are usually much smaller and will last a shorter period due to their smaller size.

I am not advertising for BlueDriver but for $99 this is a very good little device. With it you can see the wave pattern of the o2 sensors IF I repeat IF this function is available for your vehicle.

 

My dad's 2001 Tacoma is throwing this code. How many o2 sensors are there total? He wants to try and replace those before the cats

Thank you​

 

Two. But if you're going the shotgun route change the front one first. Pre cat. It's called an air fuel ratio sensor. About $80 for a Denso brand which I think is OEM. That fixed my P0420. But I broke a mounting stud in the process of removing the old one so be prepared for contingencies, especially if your vehicle is rusty. Mine was not and it still broke off the stud.

 

Can you walk me through how to change it on a 2.7L?

So air fuel ratio sensor in front is same as oxygen sensor ?

 

Thank you very much. I will let him know.

 

In between the exhaust manifold and the cat is a sensor mounted to the pipe by two nuts. Remove the nuts and disconnect the sensor and reverse to re-install. Easy. If the nut doesn't rip the stud out of the pipe.

 

Hey all, I know this ended a while ago, but some added information for people who are looking up fail codes P0420 & P0430. First things first, try reseting check engine light. If your check engine light isn't blinking you got nothing to worry for in the short term. A common cause for these error codes is not screwing your gas cap tight enough or leaving it off after the pump.

 

Mine is throwing the same code P0420 and I had recently just got a oil spray bath the day before it came on would this have anything to do with it?