Tuesday, June 29, 2010

Engine Speed Sensor R&R

Or it is also known as the crankshaft position sensor.  As stated in my last post, I needed to replace the engine speed sensor on the Touareg because it was not starting every time.  Anyway, here is a little write up on how to replace this sensor.

First of all, here is a bit from my manual which does not shed enough light on how to get this done. 

Volkswagen Touareg 
ENGINE PERFORMANCE 4.2 Liter V8 5V Generic Scan Tool, Engine Code(s): AXQ, BHX 

Engine speed (RPM) sensor, checking 
The Engine Speed (RPM) Sensor -G28- detects engine speed and reference marks. Without an engine speed 
signal, the engine will not start. If the engine speed signal fails while the engine is running, the engine will stop 
Recommended special tools and equipment  
VAG1526 multimeter or VAG1715 multimeter  
VAG1594 connector test kit  
Wiring diagram  
Test requirements  
Ground (GND) connections between engine and chassis must be OK.  
Ignition switched off.  
Test sequence  

Disconnect gray 3-pin harness connector (arrow) to Engine Speed (RPM) Sensor -G28-.  
Measure sensor resistance between terminals 2+3 at connector to sensor.  
Specified value: 480 to 1000 ohms 
Check sensor for short circuit between terminals 1+2 as well as 1+3.  
Specified value: infinity ohms 
If specified values are obtained: 
Check wires according to wiring diagram. Refer to Checking wiring.  
If specified values are not obtained: 
Replace Engine Speed (RPM) Sensor -G28-.  
Erase DTC memory of Engine Control Module (ECM). Refer to Diagnostic mode 4: Reset/erase 
diagnostic data.  
Generate readiness code. Refer to Generating readiness code.  
Checking wiring 
Connect test box to control module wiring harness. Refer to Connecting test box for wiring test
Check wires between test box and 3-pin connector for open circuit according to wiring diagram.  
Terminal 1 + socket 108 
Terminal 2 + socket 90 
Terminal 3 + socket 82 
Wire resistance: max. 1.5 ohms 
Also check wires for short circuit to each other.  
Specified value: infinity ohms 
If no malfunctions are found in wires: 
Remove sensor and check sensor wheel for secure fit, damage, and run-out.  
If nothing seems to be wrong with the sensor wheel: 
Replace Motronic Engine Control Module (ECM) -J220-. Refer to Engine Control Module (ECM), 
NOTE: There is a larger-sized gap on the sensor wheel. This gap is the reference mark 
and does not mean that the sensor wheel is damaged. 

After reading that and looking at a couple of pictures, it was still not clear what it took to remove and replace this sensor.  I definitely knew how to test the sensor.  Here is the engine bay before I started.

Then I removed the plastic covers.

I had to buy spring clamp pliers to remove the spring clamps of the intake hose.

I then removed the intake hose.

Not very much room to work with behind the engine.  This is where the upper connection of the sensor is located.  As you can see in the second picture.

You can see the gray connector in the mirror.  Not an easy location to get your hands.   

I also removed the bottom plastic cover.

I also removed part of the hood support so that I had better access.

This process in total took me about 1.5 hours to complete.  Not too bad.  The part cost about $115 and the dealer would get about 2 hours of labor or about $200.  


The Volkster said...

It has been about 3 weeks since I have replaced the engine speed sensor and no starting issues since.

Liquid Rubber said...

I hope you will not face this engine starting problem any more.

The Volkster said...

Still no issues since July when I installed the new sensor. All is well for this problem.

Anonymous said...

What you replaced is indeed the engine speed sensor. The cam shaft position sensor (crankshaft) is a different part see diagram...

The Volkster said...

Anonymous, I am not sure what you are talking about as the camshaft sensor is a different sensor from the crankshaft sensor. I stated in my post that the engine speed sensor is sometimes referred to as the crankshaft sensor. Camshaft and crankshaft are way two different things.

Chris Way said...

Hello ... replacing my sensor now. Did you have any trouble removing the connector from it's mount? I am able to easily disconnect it from the female end, it is just difficult to remove it from its mount.

The Volkster said...

Hey Chris, yes it was difficult mostly because it is difficult to see what you are doing when removing it. I tried removing things as much as I could to see better. Tried mirrors and all. I kept looking at the manual pics to see what it looked like. I eventually got it. Keep at it, you will get it removed. Then you have to install it which a bit easier than coming out.

Drewboy said...

Is it the same location on aV6 and V8?

The Volkster said...

I don't believe so as they are different engines. But I have not researched it to know for sure.

Unknown said...

Is the engine layout the same on the 4.2 phaeton? Would the sensor be in the same spot

The Volkster said...

I believe that the layout is the same between the 4.2 Phaeton and the 4.2 Touareg.