O2 sensor slow response? P0133

[Diocletian]

Received P0133 on startup. Car is running an E85 Race tune from Lund. Lund says the tune looks good, I didnt notice any visible vacuum leak when looking around the engine. Car is brand new with 4500 miles(2018 GT) as well so it is not the O2 sensor getting dirty or malfunctioning either. One thing of note, I put in a K&N performance filter like 2 weeks after I bought the car, so it's been on the car since before the tune for a total of 6 weeks.

I do notice a whistle coming from the intake after 2K RPM, Im sure thats normal but where else should I look?

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[Diocletian]

I'll add that it didnt throw a CEL, I was just scanning for codes after a rough start. I'm not going to try to get a free replacement from Ford as the car is tuned. I could get a upstream O2 sensor but they are a pain to find, I did find this after searching, will this work: https://www.cjponyparts.com/ford-ox...EPYIOdhlHAEDQU3y_1v57m28i8e7e7lxoC9uQQAvD_BwE

Still, an O2 sensor going bad on a 2 month old car doesnt make sense, anything else I can check?

 

[growler]

it wont stay cleared? it get one every once in awhile but its usually a few weeks between them and it popping up every once in awhile is normal on e-85 especially after filling up as it rereads the fuel content and adjusts

 

[Diocletian]

it wont stay cleared? it get one every once in awhile but its usually a few weeks between them and it popping up every once in awhile is normal on e-85 especially after filling up as it rereads the fuel content and adjusts

It only happened once so far, it's cleared for now, been running E85 for like 3 weeks

 

[growler]

It only happened once so far, it's cleared for now, been running E85 for like 3 weeks

I wouldn't worry about it then

 

[Diocletian]

Ok I must either have a vacuum leak or a bad O2 sensor. Car is idling higher than it should, the RPMs are a bit erratic and sometimes get a surging at idle. I wonder if it is the filter I put in. I put in a K&N filter made for the car but maybe I didn't close the airbox cleanly?

It did take me like 30 minutes to close the damn thing when I installed it and I'm not sure if the airbox is closed correctly.

Anyone got a close up picture of their mustang gt's airbox?

 

[Myshelby3425]

Ok I must either have a vacuum leak or a bad O2 sensor. Car is idling higher than it should, the RPMs are a bit erratic and sometimes get a surging at idle. I wonder if it is the filter I put in. I put in a K&N filter made for the car but maybe I didn't close the airbox cleanly?

It did take me like 30 minutes to close the damn thing when I installed it and I'm not sure if the airbox is closed correctly.

Anyone got a close up picture of their mustang gt's airbox?

It’s not your box, happened to me on the JLT as well.

 

[Diocletian]

I should add that the surg

It’s not your box, happened to me on the JLT as well.

You're the 3rd person with this issue then. Maybe Lund really needs to look into this?

 

[Myshelby3425]

I should add that the surg


You're the 3rd person with this issue then. Maybe Lund really needs to look into this?

Aré they all Lund tunes?

 

[Diocletian]

Aré they all Lund tunes?

Yes they are. All 2018's too and at least yours and mine are A10's

 

[scottycameron]

Ok I must either have a vacuum leak or a bad O2 sensor. Car is idling higher than it should, the RPMs are a bit erratic and sometimes get a surging at idle. I wonder if it is the filter I put in. I put in a K&N filter made for the car but maybe I didn't close the airbox cleanly?

It did take me like 30 minutes to close the damn thing when I installed it and I'm not sure if the airbox is closed correctly.

Anyone got a close up picture of their mustang gt's airbox?

I threw a code with my Flex Tune running the K&N (P0174, P0171), cleared the code, switched to stock filter and have been good ever since.

 

[Diocletian]

I threw a code with my Flex Tune running the K&N (P0174, P0171), cleared the code, switched to stock filter and have been good ever since.

Interesting. I’ll have to order a paper filter and do that, car seems to be performing a bit better now

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