BMW: knock sensor, air flow meter, true bmw

Question
Where exactly are my knock sensors located so that my friend can repair it? How important is the air flow meter, and it will it cause my car to stop running? Finally is it true that i can get engine diagnostic codes from pressing the accelerator? My bmw is a 1995 318is 2dr.
I have recently had a diagnostic test done and the codes that showed up were for the o2 sensor, knock sensors and the air flow meter. I have had my entire fuel system replaced about five months ago and my belts changed. How would I know if it was time to have my timing belt changed? thank You

Answer
Your car does not have a timing belt, it runs of a chain. The serpentine belt would not cause any errors to show up on a OBD1 reader (your cars computer)...

The car will not run without the Air Flow Meter. I would replace the cheapest parts first, such as the 02 sensor. And work my way back. The Air Flow Meter can be pretty expensive...

Is your engine making a knocking sound around 2000rpm? Sometimes the knock sensors are fine but the code reader will throw out that code just cause of a bad o2 sensor. replace the o2 sensor first.

Yes its true BMW has a selfdiagnostics computer (in other words you can tap the gas pedal in a special way to get error codes)... Turn the car off.. turn the key to the position where all the lights light up but the motor doesnt start... stomp on the gas pedal 5 times. wait... your check engine light will flash once, then it will blink giving u a code. example.... it flashes once, then blinks 3times, 2times 2times 1time... the code is 3221. that number can be looked up online or in a Bently Manual to find out what it means. The codes are 4 numbers long.

Let me know if I can help you with anything else.

Emanuel