Can a new serpentine belt replaced incorrectly cause a p0340 cam position sensor to appear bad?

Question

Just had a water pump, serpentine belt and thermostat changed. Drove car and shifting was off as well as check engine light was on. Took it to have a Diagnosis reader from O'Reillys done it showed a p0171 too lean, p0300 multiple misfire, p0301 cyl 1 misfire, p0302 cyl 2 misfire, p0303 cyl 3 misfire, p0304 cyl 4 misfire, and lastly p0340 cam position sensor.  

I am a single mom and do not have a lot of money to pay for things that don't need to be changed would like an idea before take it to shop.

Thank you for your time.

Answer 1

No not the serpentine  belt, if you did the water pump , what gets replaced with it is the TIMING BELT. If the timing belt is incorrect, you set a misfire code and a cam position code.