Trying to help get my moms hf running here. was working fine yesterday. Main relay is good even swapped in mine to double check. Fuses all good only engine code im gettin and have been getting for awhile is the O2 sensor. When I turn the key to crank the car, it does NOTHING besides the main relay clicking over. Have lights radio, all power ect.. but car does not even attempt to crank. Any ideas? maybe starter solenoid?

Update: Starter Relay checks out and Push starts fine

 

check to see if the starter solenoid is getting power when you turn the key to start. If it is, then it is more than likely the starter itself.