[V6-12v] Cam Position sensor ..were back boys --

Clive Young cyoung1661 at rogers.com
Thu Nov 20 04:15:06 EST 2003

Hi Jon 

 I want you to know I am no expert , I am just going to tell you my personal research and findings. Thanks to Tom Christiansen for some excellent info and direction for testing some of my theories.

    Well there is an absolute ton I can tell you about the CAM position sensor as I have a dead one as we speak. I do not totally agree with everything said on the forum but that is okay, many opinions make for great discussion. I do not have a VAG tool but when I dump the code directly from the ECU I get 2113.. which is a bad cam position sensor. It started out as an intermittent no start condition , if I went back a day later it would start. I even had the code sometimes while driving but did not affect performance too much . At some point I was able to dump the code even though the MIL light never came on.

I do not think you need fancy test tools from Audi but it depends on how handy you are. 

The CAM sensor is on the back of the drivers side bank of cylinders, you can disconnect it right from there. You have 3 wires, battery positive, signal and ground. (  connection 1 2 and 3 respectively).My bat + was 12.5 volts with the sensor disconnected, my sensor voltage around +6v if I remember correctly (ignition on ) . This is the first check, if you don't have these you are basically looking for a short or an open circuit, disconnect at the ecu ( connector C ) end and proceed to test for this. ( signal shorted to battery + or ground within the wiring )

If you have these voltages that is a good start as the ECU is "probably" working. The CAM sensor will cause a no start condition because it actually gates the Crank sensor on starting, the ECU must see both these sensors to fire the spark and start the car. Once the car is started ( above 400rpm ) ignition is handed over to the ECU and it uses only the crank to fire the spark, the CPS then controls the injector timing.This is why you can unplug the CPS once it is started, the timing for the injectors goes to a default mode , but the car will still run ( not optimally of course  ). 

I used a diode with a 1k resistor to connect between signal and ground and looked for it to go off ( remember you have 6 volts on the sensor so it will light the diode as soon as the ignition goes on  ) . ( I built my own little break out box for 2.00 ). It did not go off which told me the sensor signal did not go low. As A confirmation I hooked up a scope and monitored the signal and it showed what my led had, no drop in signal therfore no fire of ignition.

I am 90% positive I need a sensor. When I took mine off ( a real pain as you have steel into aluminum ) I noticed little holes in the signal  pick up area of the sensor " the tape head" as someone so excellently put it. They were white holes, I am not sure if this is normal but I don't think so as they were not uniform.. They are 10mm bolts holding it in ( the sensor ), one ( the upper ) I could not even get a socket on as it is so close to the housing , I had to use a wrench. Take your time they are TIGHT. I just took small bites with my socket and wrench and it eventually came out. Once the bolts are out the sensor comes off easy.

Once removed you can either buy a new one or used. As I am fairly new to the Audi game I decided to buy used in case I am wrong about my sensor diagnosis. I got one from Nick at autox.biz ( it is actually on the way ) . He charged me $30.00 + shipping. I thought that reasonable. 

I was going to write an article for the group if my findings are correct , but it looks like I just did. 
But maybe I will include pictures on my final rev. 

Oh one other thing maybe someone can comment on. The bently says to disconnect the 4 pin harness connector from the ignition power output stage, then check DTC memmory.

2 questions - where is this connector ? ( I wish to disconnect when I am testing my new sensor with the scope as I do not want the car to start with my scope connected ). Any reason why Bently asks to do this ..about checking memmory?

Clive Young 

95 90S FWD 5SPD

Clive Young 
95 90S FWD 5SPD

Clive Young 
95 90S FWD 5SPD

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