# wiring a 4 wire o2 sensor for megasquirt



## volkstypeone (Jan 2, 2006)

are all 4 wires need? or just power and ground
wire colors are black/ white/ gray/ and white again.


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## jasonsp6 (Sep 8, 2003)

*Re: wiring a 4 wire o2 sensor for megasquirt (volkstypeone)*

Pin outs:
Black-------Sensor Output (Signal to MS)
Gray--------Sensor Ground (tie to MS Gnd)
White--------Heater (Ignition switched +12)
White--------Heater (Gnd)


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## volkstypeone (Jan 2, 2006)

aw, u are god ty so much
does it matter what white wire i pick for ground and 12v? or does it not care


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## jasonsp6 (Sep 8, 2003)

*Re: (volkstypeone)*

It doesn't matter which white wire... Internally it's just a resistor.


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## volkstypeone (Jan 2, 2006)

ty again.
do stock vw have these heater inside the o2 sensor... is there any advantage?


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## jasonsp6 (Sep 8, 2003)

All 92+ Vw's have a heated O2 sensor. Some earlier models selectivity had them. 
A heated O2 sensor will reach operating temperature faster than a single or two wire unheated one. You can use a heated O2 sensor further downstream away from the motor and it will still function properly.


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## jasonsp6 (Sep 8, 2003)

btw... a heated sensor is the minimum I would want to use for your setup. If you get the extra cash I would suggest upgrading to wideband O2 (the LC-1 Kit is nice). You can tune without it, but it will make your life easier.


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## volkstypeone (Jan 2, 2006)

yea im gonna to try too.
money is limited. but if i can find 1 for cheap.


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## SoFarKingFast (Jul 9, 2003)

Awesome info, thanks, I needed this so I could wire my wideband into my stock ECU (my Zietronix has a narrowband output for such a case.)
The Bently was difficult to decipher as to which wires were which.


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## jasonsp6 (Sep 8, 2003)

*Re: (SoFarKingFast)*

Glad the information was helpful.


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## VWralley (Mar 30, 2002)

*Re: (jasonsp6)*

a narrow band will do almost absolutly nothing for you with the MS. you are wasting your time unless you get a wideband


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## alec stensaa (Jan 10, 2008)

*Re: (VWralley)*

it heats it up, because before the car is not work it will not run right.


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## v-dub owns (Sep 18, 2007)

sorry to post but megasqurit runs off 02 sensor but i got a aem wideband. what must i do to make it run off wideband and change in the ecu from narrowband to wideband? please pm me a reply cuz ill forget to check here lol


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## turtledub (May 10, 2006)

*Re: (jasonsp6)*


_Quote, originally posted by *jasonsp6* »_btw... a heated sensor is the minimum I would want to use for your setup. If you get the extra cash I would suggest upgrading to wideband O2 (the LC-1 Kit is nice). You can tune without it, but it will make your life easier.

Do you need the whole kit including gauge or can I just wire in a wideband o2 sensor to MS?


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## need_a_VR6 (May 19, 1999)

*Re: (turtledub)*

You just need the sensor and the controller, no need for a gauge. It's how I do most installs.


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## ValveCoverGasket (Mar 20, 2002)

*Re: (VWralley)*


_Quote, originally posted by *VWralley* »_a narrow band will do almost absolutly nothing for you with the MS. you are wasting your time unless you get a wideband









was about to post this...


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## v-dub owns (Sep 18, 2007)

can somone explain how i use wideband insted of 02 sensor. like i have 3 wires off the ms harness, 02 sensor signal, 02 sensor-, 02 sensor 12v, how do i tap these to aem and which ones do i tapp? thanks a million guys


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## turtledub (May 10, 2006)

*Re: (v-dub owns)*

If I get a wideband o2 I can ditch the stock narrowband and just use the wideband with megasquirt right?


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## PSUCorrado (Sep 11, 2006)

*Re: (turtledub)*

yes


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## will_t (Mar 12, 2009)

you should just buy a wb02 http://****************.com/smile/emthup.gif


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## kickinkz (Feb 18, 2009)

I know I'm resurrecting this one from the dead, but I've got an issue with my MK3...I thought it was the sensor...replaced it with a Denso sensor....still had issues. Replaced that with another under warranty....same thing. I bought a Bosch sensor today, put it in and I still have a heater circuit issue. I tested the harness side of the lead and with it off, I have ground on the last white wire...when it's running, I have ground PLUS 12 volts at the same wire...seems like I've got a short somewhere....not sure where though...nothing's ever been messed with on that harness until I replaced the post cat o2 sensor...

Any thoughts?


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## ps2375 (Aug 13, 2003)

totally the wrong forum.

Do you have the Bently manual for the wiring diagrams and have you tried a Bosch sensor?


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## kickinkz (Feb 18, 2009)

ps2375 said:


> totally the wrong forum.
> 
> Do you have the Bently manual for the wiring diagrams and have you tried a Bosch sensor?


No idea this was the wrong forum...I was just searching for threads that may help me solve my issue...that seems to be a big deal on here, search before asking.

Anyhow, yes it's a Bosch sensor, and no on the manual...

I'll post elsewhere to find help. Thanks.


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