# DIY 02 simulator
**URL:** https://forums.speedlife.net/t/diy-02-simulator/204875
**Category:** PittSpeed Automotive
**Created:** [April 17, 2010, 9:52pm UTC](https://forums.speedlife.net/t/diy-02-simulator/204875 "2010-04-17T21:52:17Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@1bad2.8](https://forums.speedlife.net/u/1bad2.8)
#### Post date: [April 17, 2010, 9:52pm UTC](https://forums.speedlife.net/t/diy-02-simulator/204875/1 "2010-04-17T21:52:17Z")
heres some stuff to build ur own o2 simulators
the diagram and parts list im posting is for a single output sim
but if u replace the 555 timer chip and use a 556 chip u can run 2 outputs for a car with dual downstream 02 sensors or u can just build 2 single boxes
all in total if u buy all the parts from radioshack the total cost will be 18.53 to build one
if u dont use the leds in the diagram u can save 3 bucks, but it will require adjustment of the one resitor on the output line
ok heres the diagram
this includes the leds but u can eliminate them if u like
r1 and r3 = 100k ohm resistors
r2= 1m ohm resistor
r4= 10k ohm resistor
c1 - 4.7 uf capacitor
c2 = 22uf capacitor
d1/d2 are 1.7 volt red leds
now with this setup if u have 4 wire o2 sensors u will need to leave the heater circut hooked up on the o2 sensor or the ecm will throw a heater circut open code
but here is a redrawn diagram that will make it able to replace the o2 sensor completly in a 4 wire o2 application
also this is redrawn without the leds so u will have to use a higher value resistor on r3 to get the output voltage correct
i dont recall the value off the top of my head so i will have to get it for u guys later on
in this drawing r4 will have to be the same value as the resistance measure over the 2 white wires of ur o2 sensor which is the heater circut
so basically u would just ohm out across the 2 white wires on ur 02 sensor and put a resistor with the same value as what u come up with in the r4 spot
this is what one without the heater circut looks like when done ( one with a heater circut would just have one extra wire comming out of it
enjoy and if u have any ?'s just ask
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### Author:  [@Quik](https://forums.speedlife.net/u/Quik)
#### Post date: [April 17, 2010, 9:55pm UTC](https://forums.speedlife.net/t/diy-02-simulator/204875/2 "2010-04-17T21:55:12Z")
you could also just space out the 02 sensor some which slows down the pulses the 02 sensor sees thus not throwing the code. the spacer trick is less then a few bucks to do
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### Author:  [@1bad2.8](https://forums.speedlife.net/u/1bad2.8)
#### Post date: [April 17, 2010, 9:58pm UTC](https://forums.speedlife.net/t/diy-02-simulator/204875/3 "2010-04-17T21:58:42Z")
> [@Post a pic of something worth the money...](https://forums.speedlife.net/t/post-a-pic-of-something-worth-the-money/41860/105):
>
> you could also just space out the 02 sensor some which slows down the pulses the 02 sensor sees thus not throwing the code. the spacer trick is less then a few bucks to do
yeah this is mostly for cars with ory pipes or that remove the cats/ install test pipes
also cheaper then buying a new downstream o2 sensor if ur car needs one the cheapest downstream 02 for the car i did this for was 68 bucks
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### Author:  [@bgblockelcamino](https://forums.speedlife.net/u/bgblockelcamino)
#### Post date: [April 18, 2010, 6:19am UTC](https://forums.speedlife.net/t/diy-02-simulator/204875/4 "2010-04-18T06:19:17Z")
the spacer does not always work. i know on newer nissans it won’t. nice find/writeup
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### Author:  [@Quik83Z](https://forums.speedlife.net/u/Quik83Z)
#### Post date: [April 18, 2010, 7:18am UTC](https://forums.speedlife.net/t/diy-02-simulator/204875/5 "2010-04-18T07:18:20Z")
Radio Shack still actually sells electronics parts?
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### Author:  [@SixSpeed454SS](https://forums.speedlife.net/u/SixSpeed454SS)
#### Post date: [April 18, 2010, 1:46pm UTC](https://forums.speedlife.net/t/diy-02-simulator/204875/6 "2010-04-18T13:46:46Z")
> [@Quik83Z"](#):
>
> Radio Shack still actually sells electronics parts?
I thought they sold GPS & Cell Phones :dunno:
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### Author:  [@1bad2.8](https://forums.speedlife.net/u/1bad2.8)
#### Post date: [April 18, 2010, 5:09pm UTC](https://forums.speedlife.net/t/diy-02-simulator/204875/7 "2010-04-18T17:09:07Z")
not all radio shacks still sell electronic parts, from what iw as told the stores that are in like strip malls will have the stuff, but ones inside like a mall wont sell electronic parts \*shrug
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### Author:  [@Quik83Z](https://forums.speedlife.net/u/Quik83Z)
#### Post date: [April 18, 2010, 6:13pm UTC](https://forums.speedlife.net/t/diy-02-simulator/204875/8 "2010-04-18T18:13:11Z")
[www.parts-express.com](http://www.parts-express.com)
That’s where I get all my stuff…I didn’t think RS even sold any parts any more.