Misfires

[Deleted member 69311]

I just changed my upstream O2 sensors. Everything is plugged in and looked good to go. I go to start my car and everything is normal for a couple seconds then it starts misfiring and idling very badly. It didn’t stall at all. The air/fuel ratio is going nuts.

Old codes:
P0141 - O2 sensor heater circuit Bank 1 Sensor 2 (had this for a while now)
P0161 - O2 sensor heater circuit Bank 2 Sensor 2 (had this for a while now)
New Codes:
P0300 - random/multiple misfires
P0302 - Cyl 2 misfiring
P0303 - Cyl 3 misfiring
P0308 - Cyl 8 misfiring
P0316 - Engine misfire detected

I reset the codes and started it up again and they came back within a minute. I also did a KAM relearn and nothing changed.

These are the O2 sensors I purchased:

https://a-premium.com/product/2x-Up...xygen-Sensor-for-2018-Ford-Mustang-U4bFLOOBoL

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[Deleted member 69311]

SOLVED: I threw back the old O2 sensors on and the car went back to normal. I’m guessing they either sent me the wrong ones or faulty ones.

 

[ORRadtech]

More than likely the problem lies in the replacement ones being aftermarket. For some reason O2 sensors often don't do well with aftermarket. It's almost always best to go with OEM O2s.

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