I just took my F-150 1999 ext to the dealer where I live and replaced the following in my truck: I have 122K miles on it and I just bought it used, I wanted to make sure this maintenance was done with winter here

1. Plugs (Autolite Dbl Platinum)
2. New Berlin Wires
3. Changed Oil
4. Flushed Coolant
5. Tranny Fluid Change
6. Replaced fuel filter with new one
7. Replaced PCV valve with new one

Took it back in today to see what the code SES light was for and they tell me the O2's are shooting the code. The truck ran PERFECT and like new before I replaced all this, Why would this be happening. And what should I do? They suggest just replace the 2 bad O2 sensors. Do I have to?

 

Whats the code? And the "SES" (service engine soon?) light seems to be referred to here as the "CEL" (check engine light)

 

The light that shows on my gauges is called "Service Engine Soon" and the code I dont know but the dealership told me that the code was for the O2 sensors, can you help?

 

Probably, but not without the trouble code. If the light is still on take it your local Advance or Auto Zone and have them pull the code for you (they do it for free) and let us know. If the lights not on, don't worry about it until it comes back. It sounds strange for both 02's (there's actualy 4 of them, but only 2 that count) to go bad at the same time.