Mil Elims HELP

DKhorse

Founding Member
Sep 5, 2002
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Philadelphia
I was getting a reading of Cat effency from my code reader. I have shorty headers and High flow cats. I was getting this reading about once a week, then it progressed to every other day. So I got tired of deleting the code with the reader, and installed Mil elims this weekend. Well the service light went office this morning only about 3 miles from my house with the same code.

I got the mils from Dallas Mustang. I assume that it does not matter which one goes on the Passenger or drivers side, they were noy labled and looked the same?

Now what?
 
what year?

no, it does not matter which side goes on which. You might want to try this, I am going to assume that you have 4 O2 sensors, put your back O2 in the front and the front ones in the back with your mil eliminators on the back ones, if it does not show that code again then one of your front O2's were bad and you can just leave it on the back (since you made them inactive with mil elims) If it doesn't fix it then you might have something else wrong.

I think this is how it goes:
The front O2's take a reading that is recorded as a baseline and the back ones take a reading that is recorded and compared against the baseline, if the measurement from the back one is less rich, then your cats are working correctly and burning the remaining fuel left after combustion. If the mearsurment isn't any less rich then it will trip your malfunction indicator light for your cats not working correctly. I think that is right. :shrug: anyone have any comments on that, I don't know much about OBDII. :shrug: Try switching and see if that corrects it.
 
krly79 said:
what year?

no, it does not matter which side goes on which. You might want to try this, I am going to assume that you have 4 O2 sensors, put your back O2 in the front and the front ones in the back with your mil eliminators on the back ones, if it does not show that code again then one of your front O2's were bad and you can just leave it on the back (since you made them inactive with mil elims) If it doesn't fix it then you might have something else wrong.

I think this is how it goes:
The front O2's take a reading that is recorded as a baseline and the back ones take a reading that is recorded and compared against the baseline, if the measurement from the back one is less rich, then your cats are working correctly and burning the remaining fuel left after combustion. If the mearsurment isn't any less rich then it will trip your malfunction indicator light for your cats not working correctly. I think that is right. :shrug: anyone have any comments on that, I don't know much about OBDII. :shrug: Try switching and see if that corrects it.
First don't swap o2 sensors front to back. They are different. The front 2 are heated o2 sensors. They monitor air and fuel ratio. The rears are for catalyst monitoring purposes only.

Post the codes up on hear that you pulled. O2 sensor DTC's are specific to location and the problem that is occuring.
 
Venom4.6 said:
First don't swap o2 sensors front to back. They are different. The front 2 are heated o2 sensors. They monitor air and fuel ratio. The rears are for catalyst monitoring purposes only.

Post the codes up on hear that you pulled. O2 sensor DTC's are specific to location and the problem that is occuring.

:nice: I told you I don't really know anything about OBDII. I thought that they were the same. :shrug:
 
Evidently it depends on model year. I have an '03, and all 4 are heated and the identical part number. The Dealer switched front and rear on one side when trying to find the cause of a MIL that kept turning on and off. Eventually they replaced both . . and indicated 2 each of a single part number on the service receipt.
 
Don't waste your time jacking around and just get your codes pulled. If you live outside of CA, Autozone does it for free. Post the code numbers in this thread, not descriptions, just codes, and I'll personally help you troubleshoot the issue.
 
if you have relatively new O2 sensors (before cats) and they keep sending a code, take em out and spray them down with Brakleen. it'll get the gunk out and theyll work again. by the way Brakleen is good for all kinds of stuff.
 
Subscribing... Whats up Dan?

Also, DKhorse I'm assuming you cleared the EEC after you put the Mil Elims on? Three miles sounds awfully quick to complete an OBDII drive cycle and throw the code. Sounds like you may have had a pending code that timed out. Just curious. But like Dan said, post the numbers and we can help. Be sure to reset the EEC at some point during the process if you havent already.

[edit] one other thing. all four O2 sensors on the car are EXACTLY the same. The only difference is the color and keying of the connectors. period. All four are "Narrow Band Heated Exhaust Gas Oxygen Sensors". Ford calls the rears catalyst monitors, but that just describes their function on the car and that is it. They just implement the monitoring function with heated O2 sensors.
 
Yep, they sure do. And they do on mine too. Thats because of the connector color and keying. Functionally they are the same. The reason for the different color and keying is so that they will be plugged into the correct connector in the harness which is a matching color and keying. I believe the fronts are the same color/keying and it would be very difficult to plug them in the wrong spot. However its very easy to get them wrong in the back thus the color and keying. And since they have a different connector on them, they are a unique part number in Ford's system. Call them what you want, they are all narrow band O2 sensors.