service engine soon light

Go to auto zone or other auto supply, they will analyze and tell u what's wrong for free.

Ok thank you

Don't rely on autoparts store employees to tell you what is wrong with your car cause they will just try to sell you parts that you may not need. Go to the autoparts store and get the trouble code(s) read. Getting the codes read is usually a free service. Write the codes down and either use Google to research the codes or post them here.

o2 sensors are bad either up or down replace both .never included in tune up thats is servicing.

I completely agree with Bob on getting codes from AutoZone(or whoever) They can/will print them out for you if you ask. The service engine soon light will come on for literally dozens of different reasons, so you WILL need to get the specific error codes. For me('03 Expedition EB) it was the DTR sensor ($30+shipping from Amazon,$70+ from AutoZone)