How to change a cam belt ON MY CHEVROLET CRUZE 1.8 F18D ENGINE

Depends on what engine you have. 1.4 has chain, 1.8 has belt. You can check the parts list to see the belt.

https://www.obd-codes.com/p0079
https://www.youtube.com/watch?v=TUwDdBEYjD4
https://www.youtube.com/watch?v=7FJV2eI2KD0
https://www.youtube.com/watch?v=S8pvlJNUkW8
list of Chevy trouble/dashboard codes below
https://chevroletforum.com/forum/s10-blazer-diy-useful-threads-62/obdii-diagnostic-codes-p-codes-16055/

https://www.yourmechanic.com/article/p0079-obd-ii-trouble-code-exhaust-valve-control-solenoid-circuit-low-bank-1-by-spencer-clayton
If needed, make sure wiring is not a problem
https://www.youtube.com/watch?v=kCr3KabpHSc
https://www.youtube.com/watch?v=cYLX2b8vCWo

Follow the link 2008 2013 chevy Cruze Aveo Astra 1 8 1 6 Timing belt Banda de tiempo

100,000 miles

The chevy 2.0 diesel engine is run by a timing belt

Try the video at the link. It is for resetting the oil change reminder, but I suspect the timing belt replace is also on the menu if you go further.
Chevy Cruze Service Light reset With multifunction display

Code 84 means a drop in engine power. May be several reasons:
1. Bad gasoline.
2. The throttle valve.
3. Error of the onboard computer.

Set park brake..,wear safety glasses.., Raise truck front suspension and place on strong Jack stands for space..Or else crawl under it...The sensor you speak of is normally mounted above the oil pan in the engine block...The oil pressure sensor is normally at the center of block just above the oil pan..However there should also be a crank sensor but it will not be in the center of block....It should be at the rear of engine..cam sensor should be at front of engine...Look at passenger side of engine..

what will happens if coolant relay 12 missing Chevy Cruze LS 2012 ??? Please answer

most are installed in a freeze plug location on the side of the engine block with the heater power cord attached to heater in block