4.7 L Camshaft Adjuster Magnet Harness Extension
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4.7 L Camshaft Adjuster Magnet Harness Extension
Question for the experts...... Please read what I have below. Is this a real problem?? If so, (a) how does one know there is a problem? And (b) are the harnesses the correct fix? Seems to me that replacing whatever is leaking should be the best solution. Anxious to hear from you!!
Don
Mercedes camshaft adjustment solenoids commonly leak oil from the sealing ring or through the harness connector. If the solenoid is leaking from the electrical connector it should always be replaced and the harnesses included in this kit should be added at the same time to prevent damage to the main engine harness. This will save you money in the long run. It is a common failure on the 4.7L engines and all 2012-2020 Mercedes engines that use these specific magnetic camshaft adjusters where oil destroys your factory engine harness after time. This results in a $10K bill from the dealer to replace your entire engine harness. You plug this plug and play wire harness pigtail extensions from the engine harness to the sensors. When they start causing problems from oil spillage you simply unplug them and throw them away and replace with new ones. No special labor require. Unplug from the sensor and plug these in place. Save yourself a lot of headache and money!
We specifically made these to address the issue on the 4.7L M278 engine vehicles, but found out there are other Mercedes engines that use the same sensor.
Fits this part number Cam magnet sensor:
·A276 156 07 90
A276 905 10 00
Don
Mercedes camshaft adjustment solenoids commonly leak oil from the sealing ring or through the harness connector. If the solenoid is leaking from the electrical connector it should always be replaced and the harnesses included in this kit should be added at the same time to prevent damage to the main engine harness. This will save you money in the long run. It is a common failure on the 4.7L engines and all 2012-2020 Mercedes engines that use these specific magnetic camshaft adjusters where oil destroys your factory engine harness after time. This results in a $10K bill from the dealer to replace your entire engine harness. You plug this plug and play wire harness pigtail extensions from the engine harness to the sensors. When they start causing problems from oil spillage you simply unplug them and throw them away and replace with new ones. No special labor require. Unplug from the sensor and plug these in place. Save yourself a lot of headache and money!
We specifically made these to address the issue on the 4.7L M278 engine vehicles, but found out there are other Mercedes engines that use the same sensor.
Fits this part number Cam magnet sensor:
·A276 156 07 90
A276 905 10 00
Last edited by atazman; Jun 5, 2023 at 06:48 PM. Reason: clarification
Member
Joined: Mar 2012
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2004 SL500 // 2015 S550
Yes, I recently installed new camshaft adjustment solenoids and camshaft sensors. 8 in total. Also added the pigtails which are designed to stop any "wicking" of oil from the sensors back to the ECU.
My car is a 2015 w 46k miles. I believe the issues may be more prevalent in the 75k + mile range. But several of my sensors were wet when I unplugged them so I changed everything out.
I too only recently learned of this issue and jumped on it. There are some great write-ups within this forum, and good vids on YouTube as well covering this issue w the M278 engine.
My car is a 2015 w 46k miles. I believe the issues may be more prevalent in the 75k + mile range. But several of my sensors were wet when I unplugged them so I changed everything out.
I too only recently learned of this issue and jumped on it. There are some great write-ups within this forum, and good vids on YouTube as well covering this issue w the M278 engine.
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2004 SL500 // 2015 S550
I actually only added the pigtails to the cam solenoids although I think they can be added to the cam sensors as well. My can sensors had more oil seepage than the solenoids.
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Are the pigtails the same for magnets (solenoids) and the sensors for a 2015 S-550 with the M278 engine? I just pulled the connectors on mine with 57K miles; all connectors were dry. Where are people buying the pigtails? Thanks in advance.
Don
Don
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2019 S560, 2015 Honda Civic Hybrid
Two different pigtails ... one has two wires, the other has three wires. Basically need four of each.
A guy on EBay was selling a kit ... https://www.ebay.com/itm/17091548172...kAAOSwyb1jWuLX
A guy on EBay was selling a kit ... https://www.ebay.com/itm/17091548172...kAAOSwyb1jWuLX
Thread Starter
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Thanks to everyone for responding. I did check my connectors and confirm both 2-wire and 3 wire connectors. For the life of me, I can't see how oil would wick up the wires into the wiring harness and ECU. But others have seen it happen. It must do it.
On another note.....does anyone know how the "pigtails" prevent the wicking action?? Or are they intended to stop the wicking? Let's say I install new sensors and solenoids, along with adding the "pigtails". What then........Is it a situation where you should replace sensors/solenoids and pigtails if you ever see oil in the connector again?
Thanks again,
Don
On another note.....does anyone know how the "pigtails" prevent the wicking action?? Or are they intended to stop the wicking? Let's say I install new sensors and solenoids, along with adding the "pigtails". What then........Is it a situation where you should replace sensors/solenoids and pigtails if you ever see oil in the connector again?
Thanks again,
Don
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2019 S560, 2015 Honda Civic Hybrid
Your questions are the same as mine. I could see oil moving through the harness by gravity, but not by wicking action. Apparently the pigtails are sacrificial; if they get oil in them they can be removed and presumably the harness itself is still dry.
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2004 SL500 // 2015 S550
I believe this is correct as well. The plugs act as an isolator, breaking continuity between the sensors/solenoids to the engine harness.
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All Cars Lost To Hurricane Isaac (W124 E420 revived - added 88 Allante 14 S550, 17 S63
The wicking action can not cross the contacts at the pigtail-original harness interface. The pigtails are sacrificial as they will wick and eventually become oily. I believe that one could soak the short pigtail in an electrically safe solvent at that time, but probably best to replace.... again... hopefully many miles later.
Thanks to everyone for responding. I did check my connectors and confirm both 2-wire and 3 wire connectors. For the life of me, I can't see how oil would wick up the wires into the wiring harness and ECU. But others have seen it happen. It must do it.
On another note.....does anyone know how the "pigtails" prevent the wicking action?? Or are they intended to stop the wicking? Let's say I install new sensors and solenoids, along with adding the "pigtails". What then........Is it a situation where you should replace sensors/solenoids and pigtails if you ever see oil in the connector again?
Thanks again,
Don
On another note.....does anyone know how the "pigtails" prevent the wicking action?? Or are they intended to stop the wicking? Let's say I install new sensors and solenoids, along with adding the "pigtails". What then........Is it a situation where you should replace sensors/solenoids and pigtails if you ever see oil in the connector again?
Thanks again,
Don
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From: unbegrenzt
2017 GLE350 4MATIC
Oil moves through the harness by capillary action. Gravity is not relevant in this case. Google capillary action (Wikipedia is good) and report back.
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Don
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Don, the pigtails approach is the MB standard solution to the problem.
They were first issued for this common problem with the M271 (4 cyl) engine, also used for the rare case on the M272/M273 ones. Unfortunately, the problem has become a common ocurrence with the M276/M278/M157 as well. Is it a permanent fix? I see it as a time delay if the sensor or solenoids start to leak.
I have read similar issue with other brands
They were first issued for this common problem with the M271 (4 cyl) engine, also used for the rare case on the M272/M273 ones. Unfortunately, the problem has become a common ocurrence with the M276/M278/M157 as well. Is it a permanent fix? I see it as a time delay if the sensor or solenoids start to leak.
I have read similar issue with other brands
Thread Starter
Newbie
Joined: Sep 2004
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Don, the pigtails approach is the MB standard solution to the problem.
They were first issued for this common problem with the M271 (4 cyl) engine, also used for the rare case on the M272/M273 ones. Unfortunately, the problem has become a common ocurrence with the M276/M278/M157 as well. Is it a permanent fix? I see it as a time delay if the sensor or solenoids start to leak.
I have read similar issue with other brands
They were first issued for this common problem with the M271 (4 cyl) engine, also used for the rare case on the M272/M273 ones. Unfortunately, the problem has become a common ocurrence with the M276/M278/M157 as well. Is it a permanent fix? I see it as a time delay if the sensor or solenoids start to leak.
I have read similar issue with other brands
I appreciate your thoughts.
Don
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From: Palm Beach, Fl
2016 S550 sport, 2018 GLC300, M3, Zo7, 2021 Sierra Denali
Well, I had bought the extension harnesses a few months ago and finally did them today when doing my oil change. I have a 2016 S550 that was babied by the previous older owner with just 27,000 miles when I bought her. Second car here and overly maintained, no hard use at all. I figured this was preventive maintenence and I wasn't as likely to have the issue. Well........I was wrong! I did all 8 and one of the top cam sensors on the drivers side was oiled up! I cut back the insulation and it appears I caught it early on. It was only 3" back with oil from what it seems. Ordering the cam sensors now.
So if you were on the fence.....its going to happen at some point...address it now. Or its happening and hopefully you catch it before it gets to the computer or ruins your whole harness.
So if you were on the fence.....its going to happen at some point...address it now. Or its happening and hopefully you catch it before it gets to the computer or ruins your whole harness.
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From: Oregon
2014 S550 4Matic, 2015 ML400 4Matic, 2019 E450 4Matic Wagon
Thanks, juanmor40. I suppose I should go ahead and install pigtails. Maybe MB does consider them a permanent fix. If you look at the internet pictures of the pigtails, you can see open areas around the wires. That is, the wires are not encased (sealed) in an outer shield. Seems the oil would have less tendency to "wick" without an outer shield sealed tightly around the wires. And..... if the pigtails are not a permanent fix, a time delay is better than nothing.
I appreciate your thoughts.
Don
I appreciate your thoughts.
Don
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From: Aridzona
'15 S550, '10 E350 P1/P2, '02 ML320
Just did mine last weekend, replaced all sensors and adjusters and installed all 8 pigtails. There was a bit of oil on two of the sensors, but nothing at the ECU connector end. 103k miles.
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From: Oregon
2014 S550 4Matic, 2015 ML400 4Matic, 2019 E450 4Matic Wagon
This is the most comprehensive thread on the oil issue with the cam sensors and solenoids and the damage that can occur. I was wrong on an earlier post. The damage to the wiring harness and ECU can be $10,000 not $20,000 that I said earlier, still a big hit to me. Great information in here. Be sure to watch the video
https://mbworld.org/forums/mercedes-...ml#post8718216
https://mbworld.org/forums/mercedes-...ml#post8718216
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2004 SL500 // 2015 S550
cheers
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From: Aridzona
'15 S550, '10 E350 P1/P2, '02 ML320
Yes. It is super easy, with two connectors and their associated slide-locks. No resets, but the car was not running/powered on when I did the connector check.
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
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2016 S550
To be honest, you will need 8 (4 solenoid and 4 sensors) pieces of hardware, and 8 pigtails (4 for the solenoids and 4 for the sensors). I do not own an M278, but I would get the hardware from fcpeuro w/o harnesses and the harnesses from Ebay ( https://www.ebay.com/itm/170915481725). As far as I know, FCP Euro only carries the harnesses of one type, not both for this application. On the Ebay link, notice the connectors are different: 2 vs 3 pins.
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It is a big problem!
Question for the experts...... Please read what I have below. Is this a real problem?? If so, (a) how does one know there is a problem? And (b) are the harnesses the correct fix? Seems to me that replacing whatever is leaking should be the best solution. Anxious to hear from you!!
Don
Mercedes camshaft adjustment solenoids commonly leak oil from the sealing ring or through the harness connector. If the solenoid is leaking from the electrical connector it should always be replaced and the harnesses included in this kit should be added at the same time to prevent damage to the main engine harness. This will save you money in the long run. It is a common failure on the 4.7L engines and all 2012-2020 Mercedes engines that use these specific magnetic camshaft adjusters where oil destroys your factory engine harness after time. This results in a $10K bill from the dealer to replace your entire engine harness. You plug this plug and play wire harness pigtail extensions from the engine harness to the sensors. When they start causing problems from oil spillage you simply unplug them and throw them away and replace with new ones. No special labor require. Unplug from the sensor and plug these in place. Save yourself a lot of headache and money!
We specifically made these to address the issue on the 4.7L M278 engine vehicles, but found out there are other Mercedes engines that use the same sensor.
Fits this part number Cam magnet sensor:
·A276 156 07 90
A276 905 10 00
Don
Mercedes camshaft adjustment solenoids commonly leak oil from the sealing ring or through the harness connector. If the solenoid is leaking from the electrical connector it should always be replaced and the harnesses included in this kit should be added at the same time to prevent damage to the main engine harness. This will save you money in the long run. It is a common failure on the 4.7L engines and all 2012-2020 Mercedes engines that use these specific magnetic camshaft adjusters where oil destroys your factory engine harness after time. This results in a $10K bill from the dealer to replace your entire engine harness. You plug this plug and play wire harness pigtail extensions from the engine harness to the sensors. When they start causing problems from oil spillage you simply unplug them and throw them away and replace with new ones. No special labor require. Unplug from the sensor and plug these in place. Save yourself a lot of headache and money!
We specifically made these to address the issue on the 4.7L M278 engine vehicles, but found out there are other Mercedes engines that use the same sensor.
Fits this part number Cam magnet sensor:
·A276 156 07 90
A276 905 10 00
I would recommend installing these harnesses, as it takes 2min and will save you from an expensive repair bill in the future.
Hope this helps!
Last edited by Lwardy_510; Mar 12, 2025 at 02:19 AM.
