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Location of Computer and O2 Sensors.


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Where is the computer located on the T4, my intention is to do a test this weekend, and most likely will need to swap the computer where we are testing at. Also recommended tools to replace the computer.

Second question oxygen sensors I also want to test disconnecting them, What I though I heard is there are 2 of them on the exaust manifold.

Pictures would be very helpful, since the manual doesn't show a good location.

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Guest Lenny

The location of the computer is behind the drivers seat or on the T4 it should be behind the seat behind the drivers seat. You will need a 10mm socket with short extension with rachet driver and a 10mm box or open end wrench. To remove the plug from the computer, pull the grab tab or end of the plug, you will see wha tI mean, out the end about 3/4" and this will release the plug. Yes there are 2 oxygen sensors, one in the exhaust manifold before the cat converter and the other is after. You can just unplug them. Keep in mind that the computer uses the oxygen sensor information to determine if the air fuel ratio is correct for the moment by moment operation of the engine based on various conditions. The computer looks at various sensors like temperature, tps, manifold pressure, barometric pressure, etc. and controls spark timing and injector pulse width based on values in a table. The computer then looks at the oxygen sensor to see if the air fuel mixture matches the table and if not, it ajdust accordingly. The oxygen sensor sends a voltage signal to the computer telling it what the ratio is so the computer is looking for a value in x volts. Can't remember which way it is but if it's looking for say 3 volts and it gets 0 volts or 5 volts (maybe considered a default value) then the computer may attempt to adjust accordingly and cause a running problem. Not sure if the computer will know if there is no signal and not consider the sensor ratio and do nothing. In this case it should run ok otherwise it could be a problem. Someone else maybe has tried it and can respond. Good luck.


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I have disconnected my o2 sensors in the past first it will run very rich, very hard to start when cold. Then as time passes 1 or 2 months it will start to show other signs of odd running, stumbeling when you shift and possibly surging between 2000 and 3000 RPM. I hooked the o2 sensor before the cat back up and left the one after disconnected. The sensor before the cat is the main one, it tells the ECM what amount of fuel to give the engine and also where the timming should be. The signal it sends for timming is critical that is where the surge will come from. The one after the cat is for emmisions( gov. regs) you don't need it and it won't affect your ECM or the way it runs. All this is what I found out on my own T2 yours might act differiently so it is up to you what you do. I spent a lot of money trying to correct the problems that arose from my dissconecting the o2 sensors instead of just hooking them back up. I was just to hard headed for my own good.

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