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Answered by Service Writer (expert)
9,955 answers provided

I have a 2000 gmc sonoma 4.3 with 120000 miles. After I replaced the oxygen sensors my engine runs poorly. It feels like it is missing causing a significant loss of power. Does anyone have any ideas why this could be happening?

Response from dach
1 question asked

I'd want to know what the codes are in the computer for starters. Did it run rough prior to the O2s replacement?

Answered by Service Writer (expert)
9,955 answers provided

Says there is no bank one activity(driver side oxygen sensor). I do not know if the o2 sensor is bad but it should not be bad. They are ac-delco(part # afs105).

Response from dach
1 question asked

Since this happened after the replacement, you need to scrutinize your steps.

No activity?

is the connector on tight? Check it. if tight, pull it off and look for bent pin, corrosion etc.

Verify the part is right. IF so swap the old one and the new again. IF it changes, take the new 02 back and try a different brand or an OEM one. Check for a part number on the original if possible.

I agree that the new 02 shouldn't be bad, but that isn't always reality. For that matter, I have had the wrong sensors in boxes marked otherwise, application issues and on and on.

Answered by Service Writer (expert)
9,955 answers provided