It's located next to the crankshaft pulley (the timing belt is going around it). You will not miss it. There is only one sensor there.
Right near the carb
It is behind the starter, You will have to remove starter to service it,
The timing sensor is called a Crankshaft Position Sensor (CKP). It is located at the 10 O'Clock positon on the crankshaft pulley.
you not need picture the sensor is next to the oil filter
firewall side of motor above starter 10mm bolt
You can't. The engine's control unit needs it to differentiate between spark and fuel injection events.
The crankshaft positon sensor is wrong. I replaced it on my 2001 A4 fixed the problem.
because they do
It is bolted to the driver side end of the cylinder head.
There are no timing marks. The ignition timing is controlled by the ECU. There is a ring behind the crankshaft pulley that has one tooth missing. When that missed tooth goes past the Crankshaft Positon Sensor it creates an electrical pulse. This is sent to the Power Contol Module which determines the timing. Timing can't be set.
Catcher!
check you crankshaft positon sensor and or egr valve