The cam position sensor is critical to the proper functioning of the engine management system in its timing of engine events. The sensor delivers information on the position of the camshaft that actuates the engine’s intake valves to the computer, which uses that information to deliver fuel and spark at the correct time.
As you can imagine, if the air/fuel mixture in each cylinder doesn’t get lit off by the spark plug at the correct moment, the engine just won’t run right. Like all modern engines, the 1.8T relies on a host of sensors like this to operate. On the one hand, it means you can no longer tune your engine with a screwdriver. On the other, these kinds of sensors provide very accurate and robust information to the engine, allowing modern computerized engines to operate much more efficiently than older engines with improved driving characteristics and power output. In essence, computerized engine management made turbocharged engines like our 1.8T much more viable for auto manufacturers to build and sell.
Fortunately for us, the cam position sensor in the 1.8T sensor is conveniently located and fairly easy to change. In the photos below I have moved the radiator support panel into the service position, but I don’t think it’s necessary to do so.
First, remove the upper timing belt cover at the front of the engine. Simply release the two clips holding it in place. Ignore the fact that the wiring to the cam position sensor is already disconnected in this photo. Below I’ll show you what it looks like and how to disconnect it.
This is the metal clip on the other side of the cover. You’ll also need to move the two hoses that run across the face of the cover. You can simply slip them out of their supporting clips and pull the cover upward to remove it.
With the sensor removed, note the green-grey metal piece that remains attached to the cylinder head. Also note the gaps in the piece that alternate with portions of the cup-shaped “wheel” that remain, forming a set of “teeth”. As this metal wheel spins along with the intake camshaft, the teeth pass through a gap in the functional part of the sensor. Depending on whether that gap is blocked by the metal teeth or not, the sensor alters the voltage signal that it sends to the engine computer, which interprets the voltage to determine the position of the camshaft.
The trickiest part of this job is reinstalling the timing belt cover, particularly where it interlocks with the lower timing belt cover. Get the covers locked together correctly first and then you can snap the top back onto the top of the valve cover. Last, reconnect the wiring to the sensor and replace the vacuum and coolant lines that run across the upper timing belt cover.
Comments: "In the photos below I have moved the radiator support panel into the service position, but I don’t think it’s necessary to do so."
It isn't.... so long as you dont lose a bolt in the timing chain path then you have to do it to go GET the ****** bolt.... other than that I have managed to change the sensor no problem I just cannot start the engine for sh*t now.... but I don't know if it is even related since I changed it because the car wouldnt start in the beginning soo.... as you may guess I'm a little screwd... :S
December 8, 2013
Comments: Many thanks. I know it's a simple job but it's nice to see how it's done, especially when you're doing it outside in November. Why is it that these things always happen when it's either dark, cold or raining ?!
November 25, 2013
Followup from the Pelican Staff: That is the way it works I guess, the challenges stack up. Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
Comments: Does this process apply to the 3.0L V-6 in the Avant?
November 4, 2013
Followup from the Pelican Staff: No, this tech article applies to 1.8 liter engines. - Nick at Pelican Parts
Comments: very useful, thanking you heartily
September 11, 2013
Followup from the Pelican Staff: Thanks for the feedback. Glad we could help. - Nick at Pelican Parts
Comments: Is it about the same price to replace the cam sensor in a 2000 v w Passat?
September 3, 2013
Followup from the Pelican Staff: If you have the 1.8l engine, yes. - Nick at Pelican Parts
Comments: Can someone help me please? I cant get the camshaft sensor all the way in. There are pieces of metal flanged around that prevents it from alignin gto the bolt holes.
Please help me.
November 9, 2012
Followup from the Pelican Staff: Is the metal a heat shield? You may have to loosen the other fastenrs securing the heat shield to the engine, then install the camshaft sensor. - Nick at Pelican Parts
Check out some other sample projects from the book: