For those of you who are running catless like myself are probably staring at the SES (Service Engine Soon) soon and the pesky p0420 code because of it. With this you have a couple options if you want to remain cat less, #1 get custom tuning and even if you do they may not turn it off (troyer performance never did it for me anyway even though I requested it on my work sheets) and #2 the MIL eliminators which require splicing into the wires of the Oxygen sensor and soldering in a series of resistors and capacitors into each sensor which didn't really appeal to me. So I set off on how to eliminate the code, have it 100% reversible, and still have a functional SES light. This is what I came up with for my 2000 5.4L...

Tools needed:

- 7/8" wrench or 02 remover wrench
- 2 sets of 2 18mm Spark plug non-foulers (NF for short) Napa part # 730-2442 About $7 a pack
- Drill
- 1/2" drill bit

The NFs look like this:



They are the same 18mm threads that are used for the oxygen sensors. After opening the package you will notice that the hole on the bottom of the NF is quite small. You will have to drill out the the hole larger on 2 of the NFs (1 for each side) to 1/2". Should look like this:



You will then have to remove the rear most Oxygen sensor on each side. To do so first unclip it from the harness so the wires don't get all twisted when you start threading it out. Then simply use your 7/8" (or O2 remover) and thread it out. It will probably be rusted in there and a pain to get out WD40 or some other penetrating lube should make your life easier. After removing the O2 sensor, it should go together like this, and should only go together one way. Thread the drilled out non fouler onto the o2 sensor and then the other one that was not drilled out onto the drilled out one. Should look like this:



From Left to right it goes: untouched NF, Drilled out NF, and O2 sensor.

Just repeat the steps for the other O2 sensor.

All you will then need to do is reinstall the O2 sensors into the exhaust pipe, plug them back in, and reset the computer by unhooking the battery and hooking it back up. Should look like this installed:



This mod is 100% reversible and has been working like a charm for me on my truck for about the last week. Typically after resetting my computer, for whatever reason, the SES light comes back on within 24 hours in my daily commute.

I would imagine that this will work on the 04+ models as well

 

im confuzed on why this stops the CEL light from coming on? because isnt there still exhuast gas getting to the o2?

 

This is my theory...

With the NFs in there it has a space between the end of of the O2 sensor and the fast traveling exhaust that it would normally see. Because of this it doesn't read that there is a large amount of unburnt exhaust gases traveling past it thus not needing to throw a code. It would only read a small amount from that little hole in the end of undrilled NF and the "cats" appear to functioning "normally" in the pcm's eyes. This make sense?

 

It sounds just crazy enough to work! Let us know how you make out with some more drive time on it.

 

oh i gotcha. yeah i bought rear o2 sims and they dont work im throwing o2 codes...even with the sims on there do they have to be in the pipe? or i just got some crappy sims. if i got the bad sims ill prob have to do this idea. well im still planing on getting dyno tuned so ill just have them turn the code off. ha i dont think my rear o2s can even reach my exhuast pipe because of were it ends lol.

 

let us know how this holds up after a couple of weeks, cause if so this sounds a whole lot better then splicing in eliminators as i dont understand electrical stuff that well. i could definately do this.

 

Good write up.

 

glad you've got another cost effective tip you are sharing

 

Still no SES light

 

one other question. are you running just pre-cats or none at all?

 

OBX long tubes don't have any cats at all, so none.

 

It's been over a month and still no SES light.

 

Thats good man. About how many miles have you put on since?

 

ever think of the legality issues of turning the cel light off on street driven vehicles?

 

A few questions Gotts.

Mike tuned via data-logging without cats right, he didn't have a problem with that correct?

What's the advantage running without as far as performance/economy?

Some of the fastest street trucks I've seen have them.