Check engine light

**Mobius_1** · 09-30-2006, 07:20 AM

What effect if any does NOT having the O2 sensors on the recently installed exhaust pipe have on performance? The car is a 2000 WS6 with a 3 inch pipe from the header collectors(after the Y-pipe)! I was checking one day under the car after noticing a plug hanging from under the car and found out that it was the O2 sensor plug! No wonder the check engine light is on all the time! It is to my understanding that if there is is no signal from that sensor to the ECU, that the car runs on a predetermined program (open loop) and will affect performance! What are my options other that having to install them back( by the way...it was this way when purchased)

**Orcus79** · 09-30-2006, 09:39 PM

From my understanding, I'm by no means an expert, the computer uses the two O2 sensors after the cats to monitor the cats and a/f ratio laon with the front set. If there is aproblem the car will go into a preprogramed fuel map for that issue, as far as performance goes I dount it will hurt it, but its not good for the car either. Suggestion would be to get the sensors instaled or get o2 sims to take there place.

Anyone else have a better understanding?

**Nasty TA** · 10-02-2006, 06:53 AM

You need to hook them back up. This is the only way the car knows it air fuel ratio adn will just dump fuel until the o2 are hooked back up. If you do not hook them back up you will take hte chance of washing out the cylinder walls on that bank. I bet the car is running like shit and you will see a huge improvement after they are hooked back up. Don't wait any longer hook htem up now. Hope this helps man.

**shady milkman** · 10-02-2006, 11:38 AM

yea doesn't it just run really rich and fuck your performance? i'm sure i've heard that many of times

**blue99ta** · 10-02-2006, 12:33 PM

Originally Posted by Mobius_1

What effect if any does NOT having the O2 sensors on the recently installed exhaust pipe have on performance? The car is a 2000 WS6 with a 3 inch pipe from the header collectors(after the Y-pipe)! I was checking one day under the car after noticing a plug hanging from under the car and found out that it was the O2 sensor plug! No wonder the check engine light is on all the time! It is to my understanding that if there is is no signal from that sensor to the ECU, that the car runs on a predetermined program (open loop) and will affect performance! What are my options other that having to install them back( by the way...it was this way when purchased)

Which O2's Sensors? The Fronts or the Rears? The rear o2's can be deleted off of the pcm, or simulated. if its a front it needs to be pullged in. the fronts are imortant and need to be in good operation.

**SeVeReDiStOrTiOn** · 10-02-2006, 09:15 PM

Like the others said, you don't need the rear o2's. The front 2 have to be there..

**Mobius_1** · 10-04-2006, 05:35 AM

The plug I found is almost just below the driver seat!

**locodave** · 10-04-2006, 07:07 AM

Hi, Far as I know how it works. The front O2 each side, is used for engine management. Fuel mix. The ones after the cat give info to the ECM that the front one is doing it's job right. Front readings always change & computer acts on it. The rears, if the fronts are doing it's job ok. Stay at a steady reading. I've heard about ppl that use an extention to get the rear O2 away from the exaust stream so it fools the computer & every thing is ok. Passing emission tests. You disconect them & you should get a Check engine light lit. Code will be for the rears not giving a reading. dave