How TO: CEL/MIL Eliminator!

[ottawaP5]

Well, I stopped at AutoZone and checked the code. It said that there was "no activity" from the second sensor. Does that mean it's toast? I Seafoamed the engine then reset the code. It came back after about 12 miles.

Ideally there should be something to replace the second O2 rather than alter the signal.

Maybe the solder didn't stick...just take it off and check to make sure everything is soldered properly.

 

[Spooled]

Possibly, but I'm pretty sure it was a good solder job. It's weird that it worked fine for 300 miles, then threw a "no activity" code. Anyway, I just ordered an O2 sim from here:
http://o2simulator.com/24803.html

Hopefully that takes care of my problem.

 

[Lord_Zath]

It's weird that it worked fine for 300 miles, then threw a "no activity" code.

I think that's what happens for people who don't do anything to their second 02 sensor - just leave it in. So perhaps the mil isn't working at all - wrong capacitor, bad solder job, etc...

just go for the nonfouler trick. it works and is harder to screw up

 

[Spooled]

I think that's what happens for people who don't do anything to their second 02 sensor - just leave it in. So perhaps the mil isn't working at all - wrong capacitor, bad solder job, etc...

just go for the nonfouler trick. it works and is harder to screw up

I already ordered an O2 sim from o2sim.com. That's the best route IMO. I don't like the non-fouler idea. You might as well just cap off the bung and hang the O2 somewhere in the engine bay.

I honestly don't think the DIY eliminator works 100%. After doing some more research I found out that the ECU looks for more than just a voltage range.

I'll let everyone know how this sim works out. They shipped it today and I should get it in a day or two.

 

[Lord_Zath]

ok good luck!

 

[Mazdarulez]

Good Info

 

[Spooled]

Update!

Ok guys, I may have a combo that works perfectly and lets you completely remove the second O2 sensor.

First I bought a universal O2 simulator from www.o2sim.com for $25. This is NOT the same thing as using a resistor since this uses a 555 timer to pulse the signal within the correct voltage range. This takes care of the signal itself, but does not simulate the heater circuit.

Next I went to RadioShack and bought a 10 ohm / 10 watt wirewound resistor for $1.90 including tax. I soldered this inline with the heater circuit wires. Here is a diagram from o2sim.com that has been modified to show the heater circuit sim. The wire colors don't match up to the factory connector, so pay attention to the diagram. I had to use a multimeter and a service manual to figure this out. I recommend that you at least check the voltage with ignition on to differentiate between the heater power and heater ground wires.

I soldered everything together on the sensor side of the plug so that I can install and remove it simply by disconnecting it. Ideally you would pick up an extra O2 connector and make this using it, however I just cut the stock O2 off and used that connector.

Now, before you run out and do this, let me test it out for a bit. So far I haven't thrown a code, but I have only started the car 3 times and have only driven about 15 miles on it. If I do throw a code, it will most likely be for the heater circuit due to me picking the wrong resistor (I guessed that a 10 ohm / 10 watt would be the right range). If that happens, I will try a 50 ohm / 25 watt resistor.

I will try to get a couple pics up ASAP. If this works out, then people will have an all-in-one replacement for the secondary O2.

 

[Spooled]

So far so good! The car is driving great since I installed this, and still no CEL. It appeards to be working great. Time to head to RadioShack to pick up a project enclosure.

 

[Zhan]

What is the heater circuit simulator for? Is it necessary in order to use the O2 simulator, or is it just so you can go without the O2 sensor?

 

[Spooled]

What is the heater circuit simulator for? Is it necessary in order to use the O2 simulator, or is it just so you can go without the O2 sensor?

The heater circuit is what brings the O2 sensor up to its operating temperature range quickly. O2 sensors don't read correctly until they are hot. All it does is pump voltage through a heater element inside the O2 sensor.

Most O2 simulators only simulate the O2 signal. You normally have to keep the O2 sensor installed and the heater circuit wires connected. The ECU checks to make sure that there is a certain resistance in the heater circuit so it knows if the O2 goes completely bad or is removed. I just cheated that with a resistor (10 ohm/10 watt wirewound). That way the ECU thinks that everything is fine and dandy withthe second O2 sensor when in reality is is completely gone.

 

[Zhan]

So if I keep the O2 sensor connected and just use the O2 simulator without simulating the heater circuit, it'll work like a MIL eliminator?

 

[Breeegz]

FYI, for us with the Non-foulers, the step to reset our ECU is an unnessary step, the CEL will go out on its own. I imagine that it's the same way for everyone... but I don't know for sure.

 

[RaiderMS3]

I had to reset mine to get it off. And I had to reset it with the key on to accessory before discoing battery, pumping brakes, key off, letting it sit, power on.

I like not seeing that stupid light. Of course, you can take out the bulb...

 

[Breeegz]

it took a couple hours worth of driving, shut off the next day...

 

[Spooled]

So if I keep the O2 sensor connected and just use the O2 simulator without simulating the heater circuit, it'll work like a MIL eliminator?

Yes.

 

[tekkie]

cool I just ordered one as well

 

[ozmojo1]

spooled- hows your combo working out?

 

[Spooled]

spooled- hows your combo working out?

Sorry, haven't been on here for a while.

It's working PERFECTLY right now. I have been running without a second O2 for a couple thousand miles without any issues. I highly recommend this solution if you are putting custom exhaust on without a second cat. You won't have to bother with an O2 bung, plus it gets that sensor out of the flow path.

 

[ozmojo1]

I am going to attempt to do this for my second o2 sensor in my 96 mx-6. we have the same engine and exhaust system for the most part so it should work. however, my downstream o2 has two white, one black and one grey wire. how do i test to see what is what? thanks, Rory

 

[Kansei]

Sorry, haven't been on here for a while.

It's working PERFECTLY right now. I have been running without a second O2 for a couple thousand miles without any issues. I highly recommend this solution if you are putting custom exhaust on without a second cat. You won't have to bother with an O2 bung, plus it gets that sensor out of the flow path.

I've been running fine without the second O2 for about 8 thousand miles with no issues

But, now that I have the MAM midpipe and already installed a new oxygen sensor into it, I need some help. I need to know what wires on the MSP factory 2nd O2 sensor extender harness correspond to the colors on my oxygen sensor so that I can extend some wires and get it all connected. I have a yellow with blue stripe, black with blue strip, green with red stripe, and an orange. It's the same wiring colors as on my factory second oxygen sensor harness, but I don't have the original sensor to check the colors.

Also, for anyone who has an MSP, where the factory harness branches off to go to the two oxygen sensors, where does the black ground wire on the msp 2nd oxygen sensor harness get attached? I can't find a bolt in the area that is small enough to fit through the little loop connector that it came with.