Amplitude = voltage so if you were still on the same scale, the voltage comparison should be close enough. The scope might not have enough resolution to catch a drop out though.

You could rig up a toothed wheel and something to spin it for a test. For a 1 to 1 test, you would need a windowed wheel but a sprocket might be a more severe test. ( Bike sprocket , metal squirrel cage fan , knock out holes of a hole saw. )

Something haven't tried but that should work. Hold sensor close to a unshielded transformer. I'd keep a close eye on voltage using a meter, the turns ratio on the low side of a transformer to sensor might be high enough that voltage might go sky high. Typically, inductive sensors are in the 2.5 ish VDC range at idle.

If you have a high current AC load, holding the sensor close to a single wire might work. ( Not a pair as the magnetic fields will cancel each other out )

Gee, we have even outsourced NASA.


Yep, it is the type of sensor I was expecting, just like a gas M104 inline 6.



With the resistance being the same, I'd expect the parts to interchange. Did you hang a LCR meter on the sensors?

I found this part number standard a while back. It does give a window into how the MB system looks logical but isn't completely. Supposedly, one of the reasons MB bought Chrysler was to absorb the parts distribution system.

I just got Pelican to send me another sensor and RMA. If I had some free time I would rig up some experiments like that. Got to work for a living today...

I knew most of the background on the MB part system, it not only works with parts but you can also go into the WIS and look at the chapter number in WIS corresponding to the second group of digits, to find the instructions related to that system/part.

The part number that is different between the two sensors is the internal Bosch number that is off by one digit. The sensor I got from Pelican is identical in every way to the original MB sensor except the location on the mold where the MB part number would be is blank.

Replacement part on the way, we shall see if it behaves when it arrives.

Just so thankful it wasn’t the ECU that was the problem. I just got through the ($1850) transmission VGS replacement on my 2008 E320 Bluetec. That is dealer only since you have to SCN code it to the vehicle which requires verification back to the mother ship via online capable Xentry.

Well the replacement sensor arrived today. Popped it in (I’m getting real good at swapping these in and out quickly... but it sure is murder on your hands and forearms) but it too demonstrated the same behavior. Back to original sensor, engine runs perfectly.

RMA’d both sensors to Pelican and ordered up a genuine MB from the dealer, will be here Friday, stay tuned...

Is something like that literally dealer only? Do not some indies have the ability to contact the mother ship? Just curious....

They do offer the Xentry system to independent garages but it is extremely expensive.
Something on the order of $5-8k to buy the system and $20k/year to license it.

There are other options for fixing the VGS sensors. I did a bunch of research before settling on having the dealer do it.

First option is that several Chinese vendors on eBay are selling the sensors. It is not terribly difficult to change them yourself, if you are handy with a soldering iron. I was concerned that the sensors were probably second quality or counterfeit and I did not want to risk that on something so critical.

The other option is pulling your VGS and sending it off for repair. There are some companies stateside that charge in the $300-500 range for this work and a bunch in Europe charging a couple hundred Euros.

There are several pitfalls with DIY transmission work, the first is any contamination will lead to issues with the transmission. The other is that the VGS is an electrostatic sensitive device and you have to follow ESD protocols when handling it.

I have a local friend with a lift that I could have borrowed, but if the sensor replacement went wrong then the car would have been bricked and stuck on his lift. Can’t even get it out of park without the conductor plate installed and working.

After evaluating all this I just bit the bullet and had the dealer do it. No worries and if something goes wrong it’s on them.

Note that this applies to the 722.9 transmissions that were used starting in about 2006. The 722.6 as used on the W210 has a conductor plate but it is “dumb”, it just has the sensors and actuators. The transmission computer is in the control box under the hood. So there are no restrictions on changing the conductor plate and they will sell it over the counter to you.

The 722.9 transmission computer is on the conductor plate (what they call the VGS assembly). There are literally 4 wires to a 722.9: power, ground, CAN-H and CAN-L. It is also coded in the parts system as a TRP (Theft Relevant Part) and can only be released to the workshop from the dealer parts counter.

This is why I was pushing for detailed testing of the replacement and old sensor. Having one bad one is possible, two in a row isn't common.

How about a stack up of tolerances at the electrical connection? Perhaps the sensor has pins a bit short and harness connector pins too short or plastic interfering with full seating of the connector.

Doing the A B A testing shows there is a problem when replacement sensors are used but I like to drill down to the exact failure. . .and feed it back to the manufacturer ( not the seller as many times low cost parts are scraped by the seller and never are returned to the maker. ) . I've been through this a time or two or more.

Just think, somewhere out there another shop is experiencing a problem with parts / hidden problem and the customer is ready to sue, is posing all sorts of bad stuff to yelp and the net.

Thanks for the feedack.

I can certainly believe that 2 sensors in a row could have the same issue. I’m sure Pelican bought a small quantity of them from Bosch, probably ordered 8 or 10 or maybe 20 based on sales history. Bosch fulfilled the order, and I am quite sure they would have all come from the same manufacturing lot. When I called Pelican and had them send me another one, I’m sure the warehouse associate went to the same bin that he got my first one and grabbed another from that same group.

As for the connector mating issues, I investigated that while I had the harness out of the car last weekend (so that I could really see what was going on with the connector).

The sensor connector is coaxial. The contacts appear to be silver plated copper. The connection is protected from oxidation and moisture by an o-ring on the sensor body.

The contacts on the plug head also appear to be silver plated copper. The center contact on the sensor is made by a circular array of 6 or 8 spring contacts inside a shroud in the center of the plug head. The outer contact is made by spring contacts on the outer part of the plug head. There is also a barb molded into the outer plastic of the sensor, this is captured by a tension ring inside the connector shell.

While I had the sensor out of the car, I did check for floating contact by attaching my meter with alligator clips to X22:12 and X22:13 and setting it to ohms. I repeatedly plugged, unplugged, wiggled, shook, vibrated and did everything short of torture the sensor and plug combination. At no time did I lose continutity (approximately 1.1 k ohm) through the sensor.

I also checked the capture of the connector with the sensor. As soon as the plug head was placed on the sensor, even before the locking detent engaged, I had continuity.

So I think I’ve done my due diligence on the electrical connection.

All I can (and have done) is let Pelican know I have received 2 bad sensors in a row. I presume that Pelican has sufficient quality assurance protocols in place and will notify the vendor that they have received a customer complaint of a suspected defective part.

The sensors are in the hands of FedEx now on their way back to California.

I went down to the dealer and picked up my pile of parts.
Fuel valve, crankcase breather puck, injector line clips, new plug for the coolant sensor, and a new CKP sensor.

Opened up the sensor package and what do you know, it’s a Bosch 0 281 002 124 with a MB logo and part number 003 153 74 28. From the same plant in Romania.

Installed the other parts and the new sensor, and the car is running perfectly. Of course I had to purge the fuel system first so that was a little heart stopping, I forgot how hard it is to purge air out of an OM606. After nearly killing the battery it caught and fired on probably the last revolution it could muster. This set a ton of codes in the ABS, SRS, and other modules for excessive low voltage. Once I got all that cleared out the car is totally error free except for that stupid drivers seat Hall sensor on the body CAN bus. And the RPMs rock steady at 628-632.

First time this vehicle has left my house since June 17th. Took it out on the road and brought it back, still error free.

For future reference here is how to change a connector plug on the more modern engines.

First on the wire end of the plug head there is a little tiny release tab. You want to very gently pry on this while pushing the wires inward (push on the wires, don’t pull). This will remove the inner shell (with the wires and contacts still attached) from the outer shell.

Once you have the shells separated now you have to unlatch the wire retainer from the inner shell. This piece is gray and is in the shape of a C wrapped around the black body of the inner shell. You want to find the little groove in one end of the C and very gently pry up in that groove. This releases the gray clip from the inner shell. This reveals two little windows through which you can see the sides of the contacts.

Now go find yourself a paper clip and a small safety pin.

You want to insert the safety pin into the hole where the sensor pins would go if you were plugging it in. You want to take the end of the paper clip and push inward on the contact through the side window. You are compressing a tiny barb in the contact that normally locks it in place. At the same time you want to push in with the safety pin to withdraw the wire and contact from the inner shell.

Once you have both wires out then be sure to slide the old outer shell off the wire harness and then put the new outer shell over the wire harness. On the tail end of the inner shell you will see some tiny numbers, these are the contact numbers, so you get the wires in the right places. Now take the new inner shell and slide the contacts in. The barb has to face the side window. Be sure they click in. If they don’t click then draw them back out, and use the point of the safety pin to very carefully raise the barb up to about a 15-20 degree angle and try again. You may need a magnifying glass to see all this...

Once you’ve solidly inserted the wires in the inner shell, then put the plug retainer c-clip back on. Now slide the outer connector shell back over the wires down onto the inner shell and push together until you hear the click. It is keyed so it only goes one way, so if it won’t go on flip it over 180 degrees and try again.