another Trac Off issue

I have just finished my tune up, plugs, wires, fuel filter and oil. about 10 miles after i finished the trac off light came on and the car is shifting very hard the wheels are almost spinning on loose surfaces when shifting. could this just be a bad wheel sensor? The service engine soon light came on about 3 miles after the trac off and no adverse affects could this be related to the trac off? it's my girlfriends car and she is blaming me for this but i cant see any way that i coudl have caused this prblem... unless it's just a loose sensor...right?

so i checked all of the connection at each wheel, all good. unless the sensors are bad that shouldnt be the issue...right? I really hope someone has an idea of why the car would be doing this.

It could be a senser. you could get a code scanner to tell you whats wrong with it. just a thought.

I am not in the business of "code scanners" what kind would i need, where can i get one and about what would be the cost?

my air intake sensor was unplugged, and that was all... i plugged it back in and it was fine.

get one from autozone.

I have just finished my tune up, plugs, wires, fuel filter and oil. about 10 miles after i finished the trac off light came on and the car is shifting very hard the wheels are almost spinning on loose surfaces when shifting. could this just be a bad wheel sensor? The service engine soon light came on about 3 miles after the trac off and no adverse affects could this be related to the trac off? it's my girlfriends car and she is blaming me for this but i cant see any way that i coudl have caused this prblem... unless it's just a loose sensor...right?

my air intake sensor was unplugged, and that was all... i plugged it back in and it was fine

The IAT sensor is an input to the PCM and is one of the sensors the PCM uses for Transmission control.
On some vehicles, if the IAT is left disconnected, the PCM will disable Traction Control (reason the Trac light came on) and set a DTC.
When the DTC is set, the PCM will command full line pressure to the trans (reason the trans shifted hard) to prevent internal failure of the transmission.