BMWZ3

Hello everyone, long time since i've been on here, yay for Lexus. Unfortunately, i've ran into trouble. I got a P0420 code, and since then I decided to replace the catalytic converter since the car does have close to 200k so I figured that needed to be done. Sadly, this didnt take. I have read now that it could be any of the multiple O2 sensors. I'm a struggling college student, I know Lexus are expensive and why would I buy it and all that, but I know Lexus last forever and thats what I needed. So, I do work on cars and am fairly good at fixing things, so I'm not sure if anyone has any ideas or know-how to figure out which O2 sensor could be bad, or which one typically throws this light on? Any help would be greatly appreciated. I just dont have lots of money to replace all O2 sensors, being that theyre a minimum of $100 each. Thanks!

LarryParker

http://www.p0420.com/

satiger

iTrader: (1)

I had the same code and I ended replacing two O2 sensors, purchased at Amazon at $100 each. This is Denso OEM and the same sells more than double the price at Toyota/Lexus dealership. http://www.amazon.com/gp/product/B00..._ya_os_product

After that, I never got the check engine again.

exxonham

Hey man what you could do is get a cheap multi meter under $5 and test each one of your O2 sensors you only have four but your code should say Bank 1 or 2 then you would only test 2 of them that is the last and only thing it can be hope this helps

BMWZ3

Well my brother-in-law ran his OBD scanner on it and it now has P0420 and P0171. It says the O2 sensor for bank one sensor two. Does anyone have an idea where that is? He showed me the one in the front as you open the hood which we noted looked new, and then the one close to the firewall in the engine bay. Is that Bank one Sensor 2? Help is appreciated, pics welcome as well. Thanks!

dewinks

OK, so your 02 sensor has 4 wires. 2 of them power the sensor, two of them send a feedback signal in the form of voltage to the ECM. you need to find what color wires are the feedback signal wires, and check them with a multi-meter like exxonham has mentioned. When you check this sensor, you can start by putting the multimeter on resistance, or ohms, and check for continuity of the sensor. if it is an open signal, the sensor is bad. Then start the car, get it to operating temperature, and check the same two wires on the DC voltage setting (VDC). You should see a small voltage that is constantly changing over and over. If the voltage is static, unchanging, the sensor is bad. I would try this with all the sensors you can freely get at just to make sure. Alot of times if you are using a cheap scanner, the bank positions are wrong. Just don't want to see you spend money you don't have. Also, check out www.toyotapartsales.com for OEM parts. They have the best prices I've found and give a guarantee on their parts. They have been good to me. Whatever you do DO NOT put BOSH sensors in your car. ONLY DENSO!!!!

hope this helps.

BMWZ3

Where does the post cat 02 sensor wires go to? I got the sensor out but the wires go up into the floor and cant find anywhere on here where they go?

PFB

The terminal is under the front driver side seat. Need to remove seat for access

angmedic91

iTrader: (5)

+1 for PFB. Ive done this myself and had to remove the drivers seat for access.