o2 sensor simulator

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=136511
Printed Date: May 05, 2024 at 5:38 AM

Topic: o2 sensor simulator

Posted By: juavos00
Subject: o2 sensor simulator
Date Posted: April 23, 2014 at 11:47 AM

I am working on my wifes car ('03 Corolla 1.8L) and she has a code P0420. I built this circuit

posted_image

R1 100k ohm
R2 1M ohm
R3 100k ohm
R4 10k ohm
C1 4.7uF
C2 22uF
D1 1.7v@20mA LED
D2 1.7v@20mA LED

I wanted to know how to get the output lower than what I have coming out already. Currently with 12V applied I am getting an output of .000-.832v every 3 seconds. I want to lower that to about an output of .000-.590ish every 3 seconds.

I have multisim on my PC but cant figure out how to make the 555 timer work nor change some of the values, I know rookie mistake!

Replies:

Posted By: oldspark
Date Posted: April 24, 2014 at 2:22 AM

Before I comment on the circuit (like why a LED for D1 instead of a diode?), have you compared the output of the cat's o2 sensor to the front o2 sensor?

Posted By: oldspark
Date Posted: May 03, 2014 at 1:49 AM

Problem solved?

Else remove both LEDs and change R3 &/or R4.

But do NOT cause any lung or other damage by doing so.

Posted By: juavos00
Date Posted: May 03, 2014 at 2:14 PM

oldspark wrote:

Before I comment on the circuit (like why a LED for D1 instead of a diode?), have you compared the output of the cat's o2 sensor to the front o2 sensor?

I built the circuit according to the website that I was following; why they put what component where is beyond me?

oldspark wrote:

Problem solved?

Else remove both LEDs and change R3 &/or R4.

But do NOT cause any lung or other damage by doing so

yes and no. I ended up getting a potentiometer and cutting the output wire in half before it went to the O2 signal wire. I have the value right now down to .640 volts and the light has stayed off for over a week of driving! If the light comes back on, then I will increase the value on the potentiometer until I have it dialed in just right. Thank you

Posted By: oldspark
Date Posted: May 03, 2014 at 7:05 PM

I suspect that circuit has been designed by clueless people that managed to fluke a solution.

As long as you realise it is not THE way to fix the problem, and if it is the cat that is faulty (and not the o2 sensor - but that's why I asked my question) then you are pumping out lung damaging acids etc.

I'm sure that that solution here would be quite an offence and hefty fines should apply if caught.
But having said that, afaik we have no prescribed cat checking, and I use unleaded petrol in my cat-less 1960s vehicles.

Thanks for replying. I wasn't sure if you were off checking the sensor or still solving the circuit.

PS - see Casper's Electronics Inc. Clean Air Act