Engine Won't Start

Ensure electrical harness, connectors and wires are not broken or loose. Ensure battery voltage is at least 11.5 volts. Check system relay and fuel pump relay. On turbo models, check pressure switch. Check all ECU input signals.
Using a spark tester, ensure that there is spark at the plugs.
Ensure fuel pump is operating. Check fuel pressure and pressure regulator. Check for fuel line leaks or restrictions in return line.
Check injector operation.
Check induction system. Check for leaks downstream of throttle valve. Inspect duct between mass airflow meter and throttle body.
Check coolant temperature sensor operation.
Check Automatic Idle Control (AIC) valve.