What is going on when the check engine soon light comes on? I had the oil change done and they didnt change the air filter.

Because there is a fault with a sensor or other fault.Need to be diagnostic test to find fault.I would suggest check engine NOW light not soon or face major problems SOON.

you are going to have to plug in a diagnostic reader and find out what the problem is or to shut off the light . You could also drive it for 300KM and it should reset itself

if you just had the oil and filter changed..the technician did not reset the alert in the cars command module..therefor the check engine light will come on until this alert is removed from the start up sequence in the cars' computer.. get that done and it should be fine..

Don't normally 'check' these filter, just have them changed, 5 years is a long time, should be changed at regular intervals, blockage in the oil filter will damage the engine and a dirty fuel filter can lower engine performance and cause a breakdown. Get them changed, as soon as. Good luck

either have an autoparts store check it or someone you know with a code reader
http://engine-codes.com/ this website helped me alot in figuring out codes

Check the codes

Yes, When you run an engine low on oil enough to cause the light to come on then damage is being done. It sounds like you caught it just in time. I would change the oil and filter for shure as soon as possible. Then I would Change them again In a week or two. Then you should be OK.

That car should use 5W30 oil, check on the filler cap, or owners manual. If you are in freezing weather, use a synthetic oil. The Change oil light is reset by turning the key on, then depressing the gas pedal to the floor 3 times. The Check Engine light is another subject and a repair shop will need to diagnose and recommend repairs. If it has a 3.0 V6 its not that user friendly. the Cadillac Catera uses that engine.

it could be that the air filter housing is worn and thats why they said you needed a new one what that means is that you are getting to much air into the engine and will cause check engine light to come on i would replace that and then see if it goes off and then if not go to a auto zone and they check the light and see what it is and then go from there

If ou fixed whatever happened during the oil change, the light will cycle off after about 3 drive cycles.

The check enine light just tells you that you are not meeting emissions right now. Only be concerned if it's flashing. That means you are sending unburned fuel to your catalytic converter whih will overheat and self destruct.

Look for a vacuum hose disconnected and check all the onnections to sensors such as, vehcile speed control sensor, mass air flow sensor, crankshaft position sensor, camshaft poition sensor, throttle position sensor, etc. Good luck.