cturek

First, I’m new to these forums so thanks in advance to all those who participate. I’ve been on jeep forums for years and they have been extremely helping because of people sharing their knowledge and I am always thankful for that. I’m considering buying a 2014 s550 that is listed on Brning a trailer. A user posted a questions about oil ruining the ecu by traveling from a leak at the cam positions sensor down the wire and getting into the ECU. This car has under 50k miles. The user was asking if this issue has been addressed. I searched this forum but couldn’t find a sticky thread on it. Seems like everyone knows about it but I couldn’t find a good write up explaining it. Can someone either explain the issue, how to look for it, and how to address it? Curious if this is something that should steer me away from this particular year or is it a simply fix? Just need some help understanding how big of a problem this is and how to factoring it into my purchasing decision.
Thanks
Chris

carlosinseattle

If I were you, I'd budget $10K for service and repairs for this car since you can't inspect or test drive first. Low mileage is either really good or REALLY bad. But the Carfax looks clean. If the purchase price goes for under $25K it's a good deal, based on mileage and Carfax history. I'm not in the makret for anything like, but if I were I'd be very interested.

as.thompson

Here is some info regarding this that I have saved over the years.

Oil in the harness affects engines M157, M274, M276 and M278. Cam position sensors and cam magnets are the sources.

The root cause appears to be a defect related to the injection molding design of the cam sensor body. @crconsulting did a great investigation into this by cutting open known leaky sensors. Oil enters the cam position sensor and is wicked into the connector and up the harness. It is not 100% clear how the oil enters the sensor, but @crconsulting 's work has been the most informative to date.
It is a must to inspect the 8 affected connectors periodically. This is entirely fixable if caught early enough. Check connectors for oil at each oil change. Early stage oil in harness is recoverable by replacing cam position sensors and cam magnets with the latest part numbers.

95Sinned420

If the car doesn't have the issue, could be prevented by replacing the cam magnets and solenoids with new parts, then installing pigtails that go between the sensor and wiring harness. The pigtails are basically just wire extensions that prevent the oil from wicking up into the wiring harness.
If the car is already leaking oil into the sensors and oil is present in the harness, there is no telling how far up it has already traveled, whether it made it to the ECU or not, until you unplug and check the pins at the ECU. If there's oil there, the damage is done already and an expensive harness replacement is needed.
With a 2014 model, I'd be more concerned about the early m278 issues, such as the cylinder wall scoring, etc.

Here's a video kind of showing the issue:

vincheung

Personally I wouldn’t be overly concerned. Upon purchase, install the pigtails on the solenoids and the camshaft position sensors. Inspect them every 5k and replace at 10-15k for good measure.

VII

This is not a big deal, I had an M276 to 100k without any leaking.
At 50k miles unlikely to have a leak, you can just monitor at oil change or install the pigtails.
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W205C43PFL

Agree, it is not a big deal and can be prevented if it didn't already happened, unlike more serious problems like the rear main seal on the M177 for example.