95 mustang gt check engine light code 172 update

[hottwheels04]

This is an update to it seems a never ending problem. few months back I had code 176/172 to do with

176=hego (ho2s) sensor fault /always lean

172= hego (ho2s) sensor fault lean,


I figured bad 02 sensor or 02 sensors. I posted this and many agreed.


I replaced the 02 sensors check engine light went off.


Now fast forward it is back again so i rescanned it. now its just code #172. I found bad vacum hose replaced it. checked for exaust leaks and new 02 sensors and still have a lean code #172.

code 176 is gone but 172 still

172= hego (ho2s) sensor fault lean,


I can drive around town 1st through 3rd gear the light never comes on. but soon as i get the highway and in 4th and 5th gear 50-80mph the light comes on blinks goes off for 1 good minute and will blink on and off several times then come on and stay on after being on the highway.

what else could it be? could the 02 sensors even it being a new 1, is bad? i know that code is to do with passenger 02 sensor. I was thinking of buying a new one again maybe got a bad 1? cant figure out!! I even had a ford dealer and buddy who owns a shop working on mustang go through the whole car they cant figure it out.

only thing I can think of since i put new heads on it compression is diffrent so tune is old tune. is it maybe running to lean up high since on an old tune so it burned up the new sensors?

was told it could be A bad fuel pump / maf going bad? since all vaccum leaks fixed checked and new hoses. no exaust leaks and car runs fine otherwise.

 

[hottwheels04]

anybody?

 

[07GtS197]

What brand is the sensor? Have you done a cylinder balance test?

 

[hottwheels04]

What brand is the sensor? Have you done a cylinder balance test?

I bought the 02 sensors at oreillys auto parts I belive they were bosch brand. not familar with a " cylinder balance test"

 

[07GtS197]

Bosch are known to not play well in the 4.6 world so I couldnt tell you for certain whether theyre good sensors or not for your application.

http://dfwmustangs.net/forums/showthread.php?t=7908

Im not sure if the 94-95s have the capability of performing a cylinder balance test but I dont see why not.

 

[hottwheels04]

Bosch are known to not play well in the 4.6 world so I couldnt tell you for certain whether theyre good sensors or not for your application.

http://dfwmustangs.net/forums/showthread.php?t=7908

Im not sure if the 94-95s have the capability of performing a cylinder balance test but I dont see why not.

Thank you, I just bought a new set from americanmuscle.com I bought some NTK performance 02 sensors for my year. I will check this hope it works. its only cheap fix or Im back at square 1 thank you I will check it out

 

[07GtS197]

No problem. Ntk are stock so you should be good to go as long as the sensor was the issue you should be good. You can test the sensor if you want to verify its faulty.

Post how it goes.

 

[01yellercobra]

Have swapped the sensors side to side to see if the code follows? Are you running headers?

 

[hottwheels04]

Have swapped the sensors side to side to see if the code follows? Are you running headers?

No i just bought 2 new ones and put them in after I replaced the vaccum hose. So i bought a new pair of NTK. Once the weather warms up I will try that or just put the new other set in. Yeah I'm running bbk long tube headers. Just weird only time the check engine light comes on is once im on the highway and after i shift into 5th gear ( over drive) then the light will come on and go off come on and go off blink on and off. then sometimes comes on stays on until i shut the car off. once i restart it , it wont come back on.I can drive around town or just shift through 1st,2nd,3rd, 4th gear and light never comes on. but soon as i shift into 5th on the higway it does. its code 172 passenger side 02 lean

 

[white95]

Aren’t the o2 sensors in the transmission harness for 4.6’s? Have you traced the harness to see if there’s any damage to the insulation causing it to ground out and cause the CEL to come on?

 

[white95]

Yeah I'm running bbk long tube headers.

Just noticed this... Have you had the car tuned with the headers? If not, that’s is 11410% your issue. Here is why:

https://mustangforums.com/forum/4-6...aders-and-check-engine-light.html#post8140396[/URL] ]The long tube headers relocate the front O² sensors further downstream than the stock position, this requires that values in a table in the tune--the O² Transport Delay table--be made larger. The values represent the amount of time in seconds that the PCM expects a change it makes in the AFR to be reported by the O² sensors, because they are moved further from the engine with the LTs these values need to be increased by 10 to 20%.

Here are the values I usually use, a 12% or so increase. The highlighted values are the new delays, the other the stock values:

 

[hottwheels04]

Just noticed this... Have you had the car tuned with the headers? If not, that’s is 11410% your issue. Here is why:



View attachment 468

Yea the car has been previously tuned with the headers. I noticed it has both codes for the 02 sensor now 172 = h20s fault lean and 173= h20s fault rich