The G40 Cam Position Sensor (CPS) is a Hall Effects Sensor used by our AAN engine's ECU (Engine Control Unit, i.e. the Motronic Computer) to figure out where the pistons are early in the starting cycle rather than waiting for the G4 crank position sensor to come around. If the ECU does not get a cam position sensor signal, it will not fire the J17 fuel pump relay. Once the engine is running, the ECU will use the G4 crank sensor position sensor to keep track of things. If the cam sensor fails, a "2113" blink code will be thrown (into memory) and check engine light will come on. If the G40 CPS fails while running, you can keep driving but as soon as you turn the engine off, you are done. The engine will NOT re-fire until you fix the cam sensor. You might get lucky once or twice by cooling the cam sender down (try pouring water down the back of the cam belt cover) Location photo and diagrams in the URL links below. Link to info on pulling blink codes HERE

The G40 typically lives behind the exhaust cam sprocket but on the very early AAN engines, it was located in a vestigial distributor ("tuna can" underneath the intake manifold, driven off the intake camshaft, much the same as a 7A or 3B engine):



Here is what the early AAN "Tuna Can" Hall sender case looks like in the engine bay:



Here is the Early AAN Hall Sender in a can out of the engine:



Here is the end of the AAN intake cam (in the right hand photo, the left hand photo is a 3B) showing the gear driving this Cam Sensor in a can:


Photo: Thanks to Jari Aalto

Here is what the later AAN and ABY and ADU Hall sender looks like:



This is what VAG says about the G40:



The connection to the ECU is via Pins 12 (power) and Pin 8 (signal)


If your cam sensor fails, you need to replace it with a new 034905161, complete with bracket, as shown here (item 10):



** OR **

Purchase just the Hall Sender (HME301)

from BB AutoMacao

Installation of either the new OE part, or the BB AutoMacao sender (on your OE bracket (be careful prying the bracket away from the head, they will break) has been excellently documented by Nate P. (ImQuattro) HERE

The VIN breakpoint for the "Tuna Can" hall sender occurs in about mid-February 1992, as discussed HERE

From time to time, with age, the Cam Position Sensor connectors get brittle and break, either at the harness end or the cam sensor itself. The harness connector with the female pins is PN 443906233, as shown here, as item 15 below and item 21 below that:





The cam position sensor connector has the male pins. The OE cam sensor pins are "potted" in the connector and cannot be removed. If the connector crumbles, it can be replaced by the Item 22 443906247 male pin connector above, along with separate pins and sealing grommets. Alternatively, VW Golf/Jetta III three pin O2 sensor connectors can be used in this application (some splicing might be required).

This will be on the exam