Can Exhaust Sensors Be Turned Off?

93lx5.0 said:

I purchased my GT500 a few weeks ago, and love the hell out of it. The thing is a monster!! But twice now I have taken it to get the emissions tests, and twice it has failed because they don't get a reading from 3 monitors when they plug it in. At first they told me to drive it for 80-100 miles or so to reset the sensors, but I did that and brought it back the 2nd time with the same result. The monitors that are the issue are the Catalyst (CAT), The Oxygen Sensor, and the Heated Oxygen Sensor. The car is definitely not stock (mods in my sig), but unfortunately it didn't come with a tuner. As far as I can tell, there is a catted midpipe in there. Could there be a custom tune that turns off those sensors for some kind of performance gain? Would I need to buy a tuner and a custom tune and replace what's on there? Thanks.

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I've no idea what resetting an 02 sensor would look like. As far as I know, they either work or they don't work. They may just need to be replaced but if that were the case, it should be spitting out codes and you should have a Cel light on.

Chances are that you do have a tune of some sort. Maybe someone more familiar with your year knows of a way besides going to dealership to find out. I don't believe that the sensors can just be deactivated through a tune but can however, be ignored (I could be wrong about this part).

If you know that the x-pipe is after-market then it's a forgone conclusion that something was done to the tune to make the EEC happy with the change.


Do you have an OB2 code reader? You might want to get one and I would DEFINITELY purchase a hand held tuner for that car if for no other reason than to ensure that you can undo anything that might happen at dealerships etc. I would be careful about popping into the dealership to have them check too. I'd be concerned that they would inadvertently flash the existing tune without knowing what's in it then be unable to fix the mistake.

Are there any Mustang performance shops near you?

Were it me, I would do myself a favor and buy a tuner from Ford.

They will likely flash you back to stock before applying any of the Ford performance tunes.

A quick way to find out for sure is to call one or two of the dealerships in your area to see what they have on hand. A work mate of mine not all that long ago ditched a Bully Dog tuner for his Ford Diesel. He bought the Ford unit to replace it with. That is what they did to his vehicle. His emissions alteration was ALSO the removal of the cats.

What Ford will NOT do is remove the cats for you. Much of that depends on the laws in your state. You may have to reach out to a Ford dealership outside of an emissions controlled county or put cats back on before they will touch it but I'm not 100% sure on this portion. There were no emissions enforcement in the county that we were in.