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Discussion Starter · #1 ·
On Sunday I installed my solo exhaust with the high flow cat and the qz resonator and the mach muffler. The install went well nothing was missing and the instructions were great. I had to lift the back end up off the ramps since the car is lowered there wasn't enough clearance under the rear axle to fit the mid pipe.

Anyways I was driving the car on Monday and the check engine light went off. I check the what it was with a scanner and said o2 sensor no activity. I am led to believe that means the o2 sensor is not getting a reading at all. I am wondering if my o2 sensor is defective or if I might have a small exhaust leak or what. I am open to suggestions and ideas to try to get this resolved.

Side note, the solo system is awesome, like most described it has a low tone that is really opens up when you give it gas. With the high flow car it sounds like a monster.
 

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I wonder if you somehow damaged your O2 harness during the install. They were very careful with the test install to make sure they didn't tug on it. The O2 is connected via two really thin wires covered in a heatshield.

You also have to make sure the harness doesn't rub or touch the exhaust. I havent seen the install instructions for the HF cat but it's obvious and can be overlooked.
 

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Discussion Starter · #3 ·
I thinking something happened on the install. Strange thing is that after I clear the error, the sensor doesn't turn on unless i drive it for awhile, if I make several short trips it wont do anything.

I just don't want to spend 90 dollars on a new one if that isn't the root problem.
 

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Just go under your car and make sure it's plugged in good and tight. Check the wire for any frays or breaks.
 

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I thinking something happened on the install. Strange thing is that after I clear the error, the sensor doesn't turn on unless i drive it for awhile, if I make several short trips it wont do anything.

I just don't want to spend 90 dollars on a new one if that isn't the root problem.
That's because of closed and open loops. The car enters closed loop and takes readings from the sensor after it's warmed up it doesn't take readings when it's cold or open loop. In open loop the mixture is more rich.
 

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Iv heard of high flow cats causing O2 sensors to "fail" they only work by compairing the first sensor(spikes) to the second (even) if it doesnt read this difference the Ecm decides something isnt working and CEl activates. there was a way to get around this by adding a resistor to the O2 sensor but I dont recall where.
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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The key is to know what the code is. O2 sensor inactive would mean the ECU is not getting a signal from the sensor or the exhaust flow is not within parameters. It is possible the exhaust through the high flow cat is giving readings that the ECU picks up as a non-functioning cat. What is the specific code you are getting?
 

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Discussion Starter · #8 ·
The code is P0140, I then looked up the code through KGIS, it gave some helpful clues but I haven't had a chance to get under the car again since I have been working so much. I appreciate all the input from the tribe. I think I need to just go under and make sure all the connections are tighten since the car had a chance to let everything settle and warm up. I will wait on ordering a sensor until I check the orginal.
 

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i recently changed the exhaust on my mustang and experienced the same problem.
your new high flow cat is dirtier than the original,so you get cel.
MIL eliminators will take care of this problem.
 

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MIL malfunction indicator light.

You can make one if you know what your doing for about 10 dollars - go do a google search.


its pretty much a resistor that'll send the proper signal to the ECM and clear the engine light, a lot of people have them on aftermarket straight pipe exhausts.
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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MIL malfunction indicator light.

You can make one if you know what your doing for about 10 dollars - go do a google search.


its pretty much a resistor that'll send the proper signal to the ECM and clear the engine light, a lot of people have them on aftermarket straight pipe exhausts.
I don't think the resistor type will work -- these only provide a constant signal to the ECU. I think the second O2 sensor is a variance-reading sensor so he'd have to use the type that moves the sensor out of the main exhaust stream -- if that is what his CEL is.

First he just needs to make sure everything is connected properly.
 

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Discussion Starter · #12 ·
Well the new cat from solo comes with a o2 sensor extension. This moves the sensor out of the pipe directly. Moves it back about an inch away.
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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Your DTC P0140 is indicating that the H02S sensor is not reading within required parameters. This means it is working so your connections are good. The cat is a three-way catalyst and the second H02S sensor is there to let the ECU know when the cat isn't working properly -- emissions related. The extension is a way of moving the H02S sensor away from the exhaust stream when it is known the high-flow cat isn't going to "clean" the exhaust as well as the original cat. If the high flow cat is not doing a good enough job of "cleaning" the exhaust you have three choices -- retune the ECU to accept the new parameters the H02S sensor reads, replace the high-flow cat with the original cat, or live with the CEL and DTC P0140.
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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no need to live with it.
get an MIL eliminator.
I'm not aware of any variance MIL Eliminators, only the constant signal type -- do you have a part number or manufacturer he could look up?
 

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Discussion Starter · #16 ·
^^^ yeah post links for help, I prefer not to live with it since I would have to get the codes regularly check to make sure that nothing else is going on with my car.
 

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If it came with the extender for the O2 you should be using it. It puts the O2 in to the correct position.

Or if you're using it you can try removing it.
 

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^^^
I agree with the above post most likley they gave you that extender for a reason if you have not put it on yet it would make sence thats why your getting a code..
also I'd check the wires to make sure there is no break in them maybe one of the conecters is lose inside the plug which would make a bit of a short...
I've already had to replace a traction control sensor plug because both wires came out of the plug part :(

if the extender is allready on then I'm wrong about that :)
and you'd need to move to plan b.
 

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Discussion Starter · #19 ·
Yeah i sould have mentioned that I installed the extension when i first installed the cat converter. I tighted the cat and moved the sensor a bit to make sure it was installed tightly. Its been two days now and no CEL, so we will see. Glas I waited and didnt rush order a new sensor.

Will keep everyone posted. I am curious to think I couldnt be the only one who purchased the high flow cat with the solo kit.
 
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