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Camshaft Position Sensor Testing
 
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Pelican Technical Article:

Camshaft Position Sensor Testing

Nick Czerula

Time:

2 hours2 hrs

Tab:

$50

Talent:

*****

Tools:

DVOM, backprobes, socket set

Applicable Models:

Mercedes-Benz E320 (2003-05)

Parts Required:

Camshaft sensor, sealing O-ring

Hot Tip:

Always note and double-check your test results

Performance Gain:

Remedy fault codes

Complementary Modification:

Replace air filter

The camshaft position sensor in Mercedes-Benz W211 models is a Hall effect type. A Hall effect sensor is a transducer that varies its voltage output in response to a magnetic field, created by the camshaft reluctor plate. The camshaft sensor acts like a switch with an on / off mode. This style of sensor provides accuracy and long life.

The camshaft position sensor is used to synchronize fuel injection and as a feedback device for engine timing. When a camshaft sensor fails, the check engine light will illuminate and a fault code will be stored. I have seen faulty sensors cause engine stalling and poor engine drivability. If you have a camshaft sensor fault code and your engine isn't running right, I suggest replacing the sensor before digging too deep.

If you need peace of mind and prefer to know why you are replacing a part, that is where this tech article comes into play. This tech article will show you how to test your camshaft position sensor with the sensor installed and removed from the engine. This way you will know if it is good or bad before replacing it. Use a high impedance DVOM when testing and good jumper wires and back probes. There is nothing worse than using junky test equipment causing more damage than good.

During the tests you will see what a working sensor will show. If your readings do not match, replace the sensor.

Remember that your car may have been serviced before and parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

On W211 models with a 6-cylinder engine, the camshaft sensor is located at the right cylinder head, mounted in the timing cover (red arrow).
Figure 1

On W211 models with a 6-cylinder engine, the camshaft sensor is located at the right cylinder head, mounted in the timing cover (red arrow).

Working at the engine cover (red arrow), pull off the two front air duct hoses (green arrows).
Figure 2

Working at the engine cover (red arrow), pull off the two front air duct hoses (green arrows).

To detach the ducts, pull them straight off the engine cover / air filter housing.
Figure 3

To detach the ducts, pull them straight off the engine cover / air filter housing. Then pull the front of the duct out of the radiator support and remove it from the engine. Repeat this step for each duct.

Lift up and remove the front engine cover.
Figure 4

Lift up and remove the front engine cover.

Then, pull the engine cover / air filter housing straight up to remove it.
Figure 5

Then, pull the engine cover / air filter housing straight up to remove it. The cover is held on by four metal clips that grab onto rubber mounts, with the front two shown (red arrows). The rear of the cover has two as well. Once detached, remove the engine cover / air filter housing from the engine.

It's a good idea to check the voltage supplied to the sensor.
Figure 6

It's a good idea to check the voltage supplied to the sensor. Without it the sensor will not operate. Unplug the electrical connector. Then turn the key to run with the engine OFF. Connect your DVOM to battery ground and measure the sensor using the positive lead. Then start at Pin 3. There should be battery volts. I always start here because if the sensor is missing battery volts, I have immediate direction.

Then measure voltage at Pin 2.
Figure 7

Then measure voltage at Pin 2. There should be 5 volts.

Then measure voltage at Pin 1.
Figure 8

Then measure voltage at Pin 1. There should be zero volts (about 0.1 volts).

Testing with sensor installed: Next we can test the sensor's function.
Figure 9

Testing with sensor installed: Next we can test the sensor's function. Start by removing the plastic cover from the electrical connector. Unclip the latch (red arrow) and remove the cover.

Testing with sensor installed: Insert a backprobe into the center pin (red arrow) (pin 2).
Figure 10

Testing with sensor installed: Insert a backprobe into the center pin (red arrow) (pin 2). Plug the electrical connector back into the sensor.

Testing with sensor installed: Rotate the engine clockwise by hand using a 27mm socket and ratchet on the crankshaft pulley bolt (red arrow).
Figure 11

Testing with sensor installed: Rotate the engine clockwise by hand using a 27mm socket and ratchet on the crankshaft pulley bolt (red arrow). Monitor the DVOM for voltage to fluctuate from 5 volts to zero volts (yellow arrow) as the engine rotates. If voltage stays at 5 volts or 0 volts while you rotate the engine, and does not fluctuate, the sensor is faulty. Sensor voltage should cycle twice per engine revolution, (0-5 volts, then 0-5 volts again, per full engine rotation).

Testing with sensor removed: You can also test the sensor with it removed from the engine.
Figure 12

Testing with sensor removed: You can also test the sensor with it removed from the engine. Turn the Key ON, but do not start the engine. Remove the sensor from the engine. See our tech article on camshaft sensor replacing. Connect your DVOM black lead to battery negative and place the DVOM on D/C volts. The red lead will be used to probe the electrical connector. Insert a backprobe into terminal 2, the middle terminal. Then connect the red lead of your DVOM to the backprobe. Hold the sensor while moving a wrench across its tip. Monitor the DVOM. Voltage should fluctuate just as it should when rotating the engine by hand. In this photo the wrench (red arrow) is away from the sensor (yellow arrow), so the DVOM reads 5 volts.

Testing with sensor removed: In this photo the wrench (red arrow) is close to the sensor (yellow arrow), so the DVOM reads 0 volts.
Figure 13

Testing with sensor removed: In this photo the wrench (red arrow) is close to the sensor (yellow arrow), so the DVOM reads 0 volts. This shows a properly functioning sensor.






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Comments and Suggestions:
Walldgreat Comments: Mine is e200 w211 kompressor 2002.
I unplug the wire from sensor and read the connector voltage.
I put the key to ignition . Read trigger pin and input voltage pin and i got 12v reading for both. Is this normal?
March 2, 2016
  Followup from the Pelican Staff: I have no experiecne with the E200,this article applies to E320. However, test results should be similar to the article. See if you can find a wiring diagram to identify each wire. Then I may be able to offer more insight, if you can share the wiring. - Nick at Pelican Parts  
Leonard Comments: Very grateful for your information. Good job.
November 28, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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