View Full Version : CDI Control Unit 642 150 5372

06-29-2010, 06:15 PM
2007, Freightliner, 906.635/642.993

Does anyone know if I can plug and play a used Control Unit or do they have to be married to vehicle which would mean I have to buy a new one?

06-29-2010, 06:18 PM
I think it has to be married.

06-29-2010, 06:25 PM
Must be some problems with these.
6421507679 replaced by 6421505372 replaced by, 6421504341 replaced by, 6421509500 replaced by 6421502330.

06-29-2010, 10:28 PM
Are you getting a DTC indicating one of the drive authorization codes?


PS: search this posting for Drive Authorization

PS: If I understand the situation correctly, you're trying to put an Engine Control Module that's already been coded to run in another vehicle. If that's the case, please review the attachment in this posting: http://sprinter-source.com/forum/showthread.php?p=98244, regarding remove/replace/programming of an engine control module.

06-30-2010, 07:53 AM
the latest part number for this unit
a6421504341 stock in germany order to vehicle details i.e vin number
uk cost 878.00


06-30-2010, 12:50 PM
I kept going in a circle with codes:
2952-001, B90/2 (Left EKAS end position measurement sensor)The valve is closed, Readout to Large.
3156-008, B5/1 (Boost Pressure sensor) Implausible value.
The test for the EKAS was confusing for me because the Actuation of M72 (Intake port shutoff actuator) would read:
Inlet port shutoff, Left-YES, Right-NO
Inlet port shutoff, Left-YES, Right-YES
The test was to hear the port shutoff move audibly and it did.
So I made a big event out of it. The levers with metal contacts the sensors read had to be the problem. After removing all the garb to put my eye on and fiddle with I knocked off one of the arms from the M72 to the left intake ort shutoff, AKA swirl flap. That became a test of nerves, many start and stops before I got that put back together.
So I moved to the B5/1, the test read it should not read more than 100 hPa difference from intake air press, atmospheric pressure. It did so I put a new one on it before the EKAS event.
After the EKAS event I went back to the B5/1 and realized what I was reading but not seeing what I was reading???
The text read, if in the event the B5/1 is disconnected the control unit would give it a fixed value of 800 hPa. WOW, on start up of the engine the B5/1 would read 950, 1100 and default to 800.
The must be a broken wire. After testing all 3 wires between B5/1 and control unit I found them all to be good. So I plugged in the old B5/1 and left it open to atmosphere and go the same reading.
At that point I realized the main engine harness has been replaced. Maybe someone has chased this before me, who knows. But I have decided the mystery with EKAS and B5/1 is the control module is spasmatic.
I feel that way enough to order a module. We will see.
Over view, Engine had burn valve and ruined cyl head. #1 only.
Blow by damaged swirl flap on #1 intake. Bought a new one which came with a new M72 (intake port shutoff actuator motor)
Injectors had been moved around and one replaced. I have learned the injectors have the ability to adjust the injection amount to the different injectors and there are numbers on each injector in which you have to plug into the computer. I am told this is important.
At the point I thought everything was fixed and went for a test drive, the truck drove good for about a mile. Then slowly had less and less response at accelerator pedal. 2800 rpm limit and would up shift very quick. I call this limp home mode. The check engine light would not come on until turn off and restart.
I hope sharing this is helpful.
I probably could have done a better job of organization but there was nothing organized about this wonderful learning experience. I am so smart now, at least while I think I know what will fix this.
I will keep you advised.
Thanks everyone for your input

07-01-2010, 04:20 AM
how about MAF ???

Actuate EGR and see if MAF changes , I say this because I just had one like this, Minus the EKAS code
also had 2633 Boost pressure regulator offset drift deviation,


07-01-2010, 12:22 PM
Thanks for the link for setting up the module. I have not seen all that information organized. A big help.

Thanks for the MAF point. I have already taken apart the module with a hope to find a cold solder joint or burned transistor or something. In the 80's I actually fixed more electronic components than not. However, mid 90's and on I may fix one in ten. The manufactures don't want us fixing anything anymore.
I will do what you suggest with the new module just so I have done it.
This basis of this project is to gain experience.


07-15-2010, 09:13 PM
Short update, Installed new ECU. Flashed it, reset injectors, regenerated soot colector and away I went.
Still no power, no kick down. After short trip hooked computer up and only one code. B5/1 which is Boost Press Sensor. In the long note above I mentioned this test.
The short of this test is from the connector at the ECU I can get the same ohm readings from pin 1, 2 and 3 of B5/1 to pins 82, 19 and 87 on ECU connector.
Let me redo that, pin 82 at ECU is pin 2 at B5/1 and so on.
I changed the ECU because I felt it was not processing provided info. Yes, before ECU I put a new B5/1 on and had same readings as old one. The test says if B5/1 disconnected it will provide a default of 800 hPa.
800 hPa is all the ECU can see from B5/1. Sometimes I catch it floating around after fresh erase of codes. It will float around 900ish to 1100ish hPa's and then in a blink it defaults to 800 hPa.
This test is done with key on, engine off. So a leak in the charge pipe would not be an issue, if it exist.
Depending how I read it, Intake Air Pressure, Atmospheric Pressure and Boost Pressure should not varey more than 100 hPa.
Atmospheric and Intake Air Pressure run 315ish hPa most of the time.
Boost Pressure usually is at default of 800hPa.
I assume 800hPa at the boost press sensor indicates hi charge pressure or hi boost toi ECU so every thing else tries to protect the engine and result is not much power.
Anyone have some thoughts.
I have ordered a 2nd new B5/1 and will plug it in tommorrow for fun.

07-16-2010, 01:53 AM
Michael, I'm sorry I can't be of more help, but I can't let the opportunity to learn on your dime pass by w/o my confirming my understanding of what's going on.

The CDI is Daimler-speak for the what up until recently was just called Sprinter engine control module electronic control unit or ECM ECU in Chrysler-speak).

Your Sprinter's boost pressure sensor is sending information to the CDI control unit indicating you're maxed out on boast and you may have no more.... thus you have no kick down and no power.

So your new CDI Control Unit is married to your Sprinter and a new boost pressure sensor, but you're still getting wonky readings from the new one as you got with the old one. You're gonna try a new boost pressure sensor (sorry, I can't translate boost pressure sensor to B5/1 as readily as you or - probably - everyone else) because you have good wiring between the ECM ECU aka CDI Control Unit and the B5/1 (hey! I did it!!).

Did I get it right?


07-16-2010, 02:06 AM
did you auto replace the CDI unit ? if so you might have contaminated the new CDI controller with bogus software .... It has happened to me before.
But ... Try to normalize the MAF sensor then clear your codes, then move to actuations and actuate boost/turbo regulator, watch the actual linkage to the turbo from the boost pressure regulator. Does it move ... if so you should be able to monitor the actual reading from the B5/1. If nothing is a happening Test the MAF the way I previously stated , Note: that the MAF reading will drop aprox. 200- 250 mg/stk during EGR actuation


07-26-2010, 06:26 PM
did you auto replace the CDI unit ? if so you might have contaminated the new CDI controller with bogus software .... It has happened to me before.
But ... Try to normalize the MAF sensor then clear your codes, then move to actuations and actuate boost/turbo regulator, watch the actual linkage to the turbo from the boost pressure regulator. Does it move ... if so you should be able to monitor the actual reading from the B5/1. If nothing is a happening Test the MAF the way I previously stated , Note: that the MAF reading will drop aprox. 200- 250 mg/stk during EGR actuation


Carl, forgive me, I am hard headed and I have been triying to improve that for 5 decades. Better late than never, in other words I am working on it.
I say this because, please bear with me, I have not done the test you suggested twice. I have no excuse but several reasons. Shop got busy, tech got sick, broke my index finger, and on and on.
I finally raised the hood today and started trying to remember where I left off.
Talking to myself, I reminded myself that there is a high probability many other shops probabally have worked on this. I also remembered my part guy telling me when we were looking up the B5/1 that there were some footnotes. Something like there has been cases where other componets on this engine can be faulty and yet the computer gives the code I am chasing.
I plugged a new boost press sensor, B5/1, in for fun and still have the 800hPa.
Standing there with a deer in the headlight look, my eyes focused on the air cleaner.
There is a sensor in the air cleaner, I looked at the part number, and looked harder to realize it is the same part number as the B5/1, however according to my info this is a B28, intake manifold press sensor.
Here is where I hope you can help again. I need to know if you can tell me the part number for this B28 sensor? I cannot see them being the same. If I am right it would make since some other shop may have ordered the B5/1 and put it in the wrong hole. I want to eliminate this mystry before I go to your suggestion.
Here is a picture.

06-06-2013, 08:24 PM
for the interest of those who read this thread up to this point and were hoping for an answer... I have been working on an 07 3.0l with the EXACT same issue, P3156 boost pressure implausible value, pressure value reverting to a preset default pressure, everything. using star parts I found the intake pressure sensor on the air box is a different part number as the boost pressure sensor. a shop previously replaced the map sensor and put it in the air box.

we ordered the correct part for the air intake pressure sensor and it fixed the problem. thank you to the thread host for the information up to the following it helped greatly in my diagnosis.


07-30-2013, 02:23 AM
Holy Buck, I'm currently Working On a 2007 Sprinter with the exact same issues and codes as this thread, trying everything to figure it out, will double check the part number on the air box tomorrow, hopefully that is the problem.

11-24-2014, 05:48 AM
Just got same issue here. However all sensors were right and in its places. Replaced with new. Wiring to ECM good. Have boost pressure 1200 drops to 950 then to 800 after fresh codes reset. If i reset code on cold, pressure won't go to 800 and stay at 1100 ( which is normal since intake and ambient pressure here are around 1000) until engine worms up to normal working temperature. So i can get a good 5 mile ride on cold.
My thoughts were wiring getting hot and loosing contact at some point... Wrong. Once i stop engine and reset code, values changes from 800 right away, will stay 900-1200 for couple minutes maybe. So it's not wiring.
Its not air related so now confused even more, since my sensors are right and in its places.
Any thoughts would be very appreciated..