Should we be reimberst if machanic was not able to correctley fix our engine on light problem

if the car is a 2,5 or 3ltr you have to remove the inlet manifold for access. check you have reconnected the wiring connectors to the throttle body/throttle motor correctley. you may also have the engine managment light on with a fault code logged for throttle position sensor. hope this helps.

Test the Battery !! They only last 4 year in some
cases,8 if you get a good one & it likes a perticular
vehicle

the on plug ignition coils can cause this problem you need the fault codes getting out the system to help diagnose correctley

I doubt the code said to replace the O2 sensor. It probably said there was an issue with the data it was sending to the computer.
Sometimes the sensor is faulty, and sometimes there is a problem with the fuel system.
The O2 sensors give the computer data it uses to adjust fuel mixture.
If you can get the actual trouble code or codes we can advise.

if its throwing a code for cam sensor but new sensor does not fix it given the fact of recently replacing the timing chain id say it sounds like the timing was not set correctly which is causing the cam sensor to receive abnormal readings throwing the check engine light on. pull cover and check timing mark placement against specifications

you might have to go to a machanic
the reset is usally in he computer or a code with the ignition

It is not in but under the steering column, when you hit your flashers or 4 ways listen for a clicking sound on driver side, it will lead you to you turn signal relay switch.

try riving up motor after flipping switch or make sure your moving maybe a vacuum leak

change the tempature sensor,it sounds stupid but it fixed my car

no when the light comes on means need service and the machanic will do that then reset the light if u did the service your self you will still have to take it to a machanic to clear the light its simple but each car is diffrent has to clear it by a number of turns from the key while holding down trip meter or so