O2 heaters and o2 monitors will not set

jared davison

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I have a 06 mustang gt and the o2 heaters and o2 sensors won’t set I’ve driven it all sorts times hundreds of miles I’ve replaced o2s I have no lights car runs great I’ve done a hard reset they will not set I’ve followed fords drive cycle they give and nothing anyone have any idea?
 

07 Boss

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What do you mean they wont "set?" Are you getting codes? Are they not coming on at all? They might be turned off. How long have you had the car? Why did you replace them in the first place? When did they stop working?
 

jared davison

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The monitor are not ready o2s are reading correctly just not setting the monitors no codes at all all it says is not ready it’s been over 500 miles of driving in the city and highway driving I’ve had the car for years and it’s been fine I changed the battery about a month ago now it’s time for inspection and it won’t pass
 

stkjock

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these cars have a very specific driving cycle that must be followed for the monitors to reset, it's linked above and also in the owners manual.
 

07 Boss

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You should still pass though with one not ready on there. I know it took a couple weeks for mine to read ready but I have a different set up.
 

Laga

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You should still pass though with one not ready on there. I know it took a couple weeks for mine to read ready but I have a different set up.
Yes, I passed with 6/7 monitors ready. At least in my state.
 

skwerl

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Last time I did mine it was cake. I live about 3-4 miles from the Interstate so after letting it sit overnight, I drove carefully without slamming on the brakes or speeding to the Interstate, maintaining about 30-35 mph between stop signs. Then I got on the Interstate and drove up one exit keeping my speed steady at about 60. Then I exited and got right back on coming back home. By the time I got home my P1000 was gone.
 

07 Boss

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The heater o2 monitor isn’t setting either so I have 2 not set

Well that sucks. The only thing I can think of is the wiring. If both your heater circuit and the sensor circuit aren't working properly I might double check the harness and test for continuity. The only other thing that comes to mind is these cars are kinda finicky when it comes to the sensors. I remember putting in some bosch replacements and having issues. At ford they even five the same part number for both front and rear sensor even though originally they came with different front and rear sensors. I know when I looked up the original part numbers and got the ones from NGK (I think), it got rid of my funky tuning issues. What sensors did you put in there?
 

stkjock

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The heater o2 monitor isn’t setting either so I have 2 not set
IIRC, as it happened to me back in 07, there’s a cascade effect with these monitors, if one fails to set, it caused one or two others to not reset, I’ll reiterate the driving cycle must be done precisely, I’ve seen it on this site for 15 years, majority of the times it resets all .
 

jared davison

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Fixed the car somehow when I changed the battery it messed up the programming in the car so I had my tuner guy come and flash a stock Tune and she passed after a little driving
 

Gabe

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Fixed the car somehow when I changed the battery it messed up the programming in the car so I had my tuner guy come and flash a stock Tune and she passed after a little driving

That's good to hear.
Before I saw this last post from you, I was reading and was gonna say, I had this issue a few years ago on my '13 GT, turned out to be the tune, the fuel trims were off. Good enough for the car to run great, but not to let the emission monitors all go ready.
I went for a drive with my tuner, he was datalogging, and saw some things that could be done better, he made some changes and within a mile or so, I had another monitor go ready.

And especially "it's the tune" if your tuner returned the car to stock and the car finally went ready ... your tuner needs to revise their tune before re-tuning your car.
Simply being tuned shouldn't make the car not go OBD-ready.
 

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