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M157 like M276 and M278 is already using piezo type injector.
The bad thing about piezo is, when power is lost to the injector while it is in OPEN/Inject state, the injector will stay open because the piezo crystal need
electrical trigger to close shut the injector. Oldie injector uses spring, so when power is loss, spring close shut the injector.
So yes, there is a possibility that the injector stayed upon for a while during the chaos the engine oil in harness did.
Piezo diagnosis can be dangerous as the injectors operate at up to 200 volts and 15 amps. If disconnected while the piezo crystals are expanding they will not be able to ground and the injector will remain in the expanded state.
Therefore, no attempt should ever be made to disconnect these injectors while the engine is running. After only a few engine revolutions enough fuel will have entered the cylinder to cause hydraulic lock and serious engine damage, not to mention the risk of electric shock. https://www.partinfo.co.uk/articles/137
Understood! Thank you all. Leakdown test came back and seems cylinder 4 is about 30-40% leakdown. So one of two things is happening or happened. One oil solenoid wasn't disconnected, cylinder wasn't getting properly lubricated and the piston rings started butting, started scoring the cylinder. Two the oil in the harness was causing an issue with the signal to the injector and it was possibly leaving injector open longer or the injector is toast. Just trying to make it all make sense. End of the day might sell vehicle and move on or replace oil sensors, wash everything well, 5 gallons of pump E85 a little hard driving and see if it misfires again and hopefully it seals the cylinder up. It only misfired one time.
Well round 2 for me at 133k. Only the sensors this time. Will check the ECU again soon. All leaked but again the ugliest is the one on the driver side closest to the center of the engine. 10 minute job. FCP lifetime warranty. Lets see how quickly I get my money back.
2004 E 500 4MATIC Wagon; 2015 ML 350 4MATIC; †2003 C 240 4MATIC Wagon (2003-2022)
Originally Posted by S. Madman
Well round 2 for me at 133k. Only the sensors this time. Will check the ECU again soon. All leaked but again the ugliest is the one on the driver side closest to the center of the engine. 10 minute job. FCP lifetime warranty. Lets see how quickly I get my money back.
Thanks for the follow-up. How many miles did the initial replacement set of camshaft position sensors go before they started to leak oil into the wiring harness?
I replaced all of my camshaft position sensors with the latest revision shortly after I had purchased my vehicle back in late 2021. Haven't had any oil leak through them or through the camshaft adjuster magnet connectors yet. I also had the connectors on the oil level sensor and oil pump control valve solenoid checked earlier in the year for oil seepage, and they were clean. I'll be checking them again early next year and will probably install the sacrificial harness extensions for those (i.e., the aftermarket ones sold on eBay...) at that time.
Update........... since my car is now 11 years old, I replaced the 4 cam-pos sensors.
I think specific to M278.8xxx 3.0 Turbo engine , we get the "safer" cam-pos sensor. The part number A2769050900 is only for M276.8xx family.
I am still waiting for info if this A2769050900 or M276.8xx engines can have its cam-pos sensor leaking oil, which M278, M157 and M276.9 3.5NA is proven to be leaking oil.
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One month special order...dugghhh.....came about in 3 weeks.
The most unpleasant one to replace. Bank 1, exhaust cam-pos sensor.
The Torx tool get kinda blocked by the turbo vacuum wastegate actuator, that round fat thingy.........
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Unless the plastic casing of cam-pos sensor cracked, no way oil can go into it and exit at the male pin terminal.
I notice the type of cam-pos sensor prone to this leak is the one with this unique vent-hole.
P/N A2769051100 and later revised to be A2769051000
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Since M276.8xx is the newest of the other trio bunch M276.9 , M278 and M157, I guess that is why my engine get the hole-less cam-pos sensor and my part number never changed.
I guess Continental finally got the resin formula or casting formula or whatever yada yada CORRECT AND they improved for my cam-pos sensor.
Not only Mercedes has this issue, but more common on Mercedes because M276, M278 and M157 are popular engines and M157 AMG engines are famous, thus more "noise".
Any M272 wicking oil out of its cam-pos sensor to ECU ?
RELIABLE 276-TT CPS: shorter body with no slots...
The Continental CPS on M276 NA has been upgraded to reliably leak oil into ECU harness.
LEAKING 276-NA CPS Longer body with slots that leak oil out into engine harness
The CPS show the nearby steel particulates carried by the oil flow are attracted by the cam sensor inner magnets... that's both good + bad. circulating fine steel shavings
This prompted me to install neodymium magnets over my filter housing to help capture magnetic material.
Strong neodymium magnets... $8.USD
I will clean up the oil filter inner surface at next oil change early Summer '26 to see how much steel has been recirculating around.
Last edited by CaliBenzDriver; Dec 1, 2025 at 11:34 AM.
I've decided to change my CPS and magnets along with the pig tails which I got from FCP. Lately, the weather has not been helpful and I was really busy so I decided to check a few shops to see how much they'd charge me to do the replacement. I was given an estimate of $900+-. I think that's too much for what appears like plug and play type of replacements of sensors and magnets. I see where most of them are located, but can someone point out to the location of all of them, and what type of difficulties I might run into if I did this myself? I looked online for video clips, found a few, but none for the W212 2014-2016.
I've decided to change my CPS and magnets along with the pig tails which I got from FCP. Lately, the weather has not been helpful and I was really busy so I decided to check a few shops to see how much they'd charge me to do the replacement. I was given an estimate of $900+-. I think that's too much for what appears like plug and play type of replacements of sensors and magnets. I see where most of them are located, but can someone point out to the location of all of them, and what type of difficulties I might run into if I did this myself? I looked online for video clips, found a few, but none for the W212 2014-2016.
I just googled an engine for W212 2014-2016 and it looks like on the right side when you're facing the engine that the oil filter is in the way of the magnets which can be easily taken out of the way, but on left it looks like some stuff in the way. I am only familiar with the W221 from 2013 S550 but will tell you replacing the cam sensors and cam mags along with installing the pig tails are probably the easiest repair I've ever done on my car. I would recommend that you get new bolts for the magnets as on mine they are aluminum and new ones will come with thread locker preinstalled on them. You never know if someone has previously torqued on them too much and since they are cheap, just get them. Be careful tightening them since they are aluminum they can snap off if too tight then you have to use an easy out to get the broken stud out. On the W221, The dealership sold the pigtail for the magnets but not the sensors, I got the pigs for the sensors from ZZ Performance on ebay.
I don't know the torque specs, just be careful as its not very much. Also when moving plastic parts out of your way if there are any, be mindful that they get brittle with heat and age from the Mercedes engine, sometimes a small plastic part can set you back on cost depending on what it is. It was a very simple job on my W221 though and I wish I could get someone to pay me $900 to do it for them as it would be very easy money.
$900 makes me think that there are some things that need taken out of the way which may be a pain in the butt, however I'm not really getting a clear picture of what they are. I circled it in red on this pic.
I just googled an engine for W212 2014-2016 and it looks like on the right side when you're facing the engine that the oil filter is in the way of the magnets which can be easily taken out of the way, but on left it looks like some stuff in the way. I am only familiar with the W221 from 2013 S550 but will tell you replacing the cam sensors and cam mags along with installing the pig tails are probably the easiest repair I've ever done on my car. I would recommend that you get new bolts for the magnets as on mine they are aluminum and new ones will come with thread locker preinstalled on them. You never know if someone has previously torqued on them too much and since they are cheap, just get them. Be careful tightening them since they are aluminum they can snap off if too tight then you have to use an easy out to get the broken stud out. On the W221, The dealership sold the pigtail for the magnets but not the sensors, I got the pigs for the sensors from ZZ Performance on ebay.
I don't know the torque specs, just be careful as its not very much. Also when moving plastic parts out of your way if there are any, be mindful that they get brittle with heat and age from the Mercedes engine, sometimes a small plastic part can set you back on cost depending on what it is. It was a very simple job on my W221 though and I wish I could get someone to pay me $900 to do it for them as it would be very easy money.
$900 makes me think that there are some things that need taken out of the way which may be a pain in the butt, however I'm not really getting a clear picture of what they are. I circled it in red on this pic.
I'm not too far from Hollywood, let's hookup and make this a joint effort
I just googled an engine for W212 2014-2016 and it looks like on the right side when you're facing the engine that the oil filter is in the way of the magnets which can be easily taken out of the way, but on left it looks like some stuff in the way. I am only familiar with the W221 from 2013 S550 but will tell you replacing the cam sensors and cam mags along with installing the pig tails are probably the easiest repair I've ever done on my car. I would recommend that you get new bolts for the magnets as on mine they are aluminum and new ones will come with thread locker preinstalled on them. You never know if someone has previously torqued on them too much and since they are cheap, just get them. Be careful tightening them since they are aluminum they can snap off if too tight then you have to use an easy out to get the broken stud out. On the W221, The dealership sold the pigtail for the magnets but not the sensors, I got the pigs for the sensors from ZZ Performance on ebay.
I don't know the torque specs, just be careful as its not very much. Also when moving plastic parts out of your way if there are any, be mindful that they get brittle with heat and age from the Mercedes engine, sometimes a small plastic part can set you back on cost depending on what it is. It was a very simple job on my W221 though and I wish I could get someone to pay me $900 to do it for them as it would be very easy money.
$900 makes me think that there are some things that need taken out of the way which may be a pain in the butt, however I'm not really getting a clear picture of what they are. I circled it in red on this pic.
The red circled part is the camshaft solenoid. The cam position sensors are on top of the valve cover, circled in yellow.
I've decided to change my CPS and magnets along with the pig tails which I got from FCP. Lately, the weather has not been helpful and I was really busy so I decided to check a few shops to see how much they'd charge me to do the replacement. I was given an estimate of $900+-. I think that's too much for what appears like plug and play type of replacements of sensors and magnets. I see where most of them are located, but can someone point out to the location of all of them, and what type of difficulties I might run into if I did this myself? I looked online for video clips, found a few, but none for the W212 2014-2016.
youll need an indoor location to keep the weather put of your way
The intake plenum will need to come off so for all your troubles I'd replace SPARK PLUGS + BOOTS and air filter at the same time.
youll need an indoor location to keep the weather put of your way
The intake plenum will need to come off so for all your troubles I'd replace SPARK PLUGS + BOOTS and air filter at the same time.
Can the intake plenum be lifted about an inch from front to unplug the sensors without having to take it all the way out? Removing this thing is not a walk in the park!
Can the intake plenum be lifted about an inch from front to unplug the sensors without having to take it all the way out?
Removing this thing is not a walk in the park!
You can try... I would if you really don't want to deal with anything else.
Don't lift plastic plenum sideways to upset the green intake seals.
It's seriously very easy to remove the intake manifold on the M276 engine. Remove the 4 bolts holding it in place (2 at the read, 2 at the front). Disconnect the vacuum yellow/black rubber line at the rear, 2 connectors on the rear left, 1 connector on the rear right, the screw from the EGR line, I think 2 connectors on the throttle valve and that's about it. Can be done in a couple of mirrors, no big deal.
I'm trying to get pig tails for the sensors, but it looks like there are no OEM ones out there. ZZ Performance on Fleabay carries pig tails for the 4.7L engines only. I was able to get OEM pig tails for the magnets, but nothing for the sensors. However, on Fleabay I found sensor pig tails, but not sure if they would work.
I'm trying to get pig tails for the sensors, but it looks like there are no OEM ones out there. ZZ Performance on Fleabay carries pig tails for the 4.7L engines only. I was able to get OEM pig tails for the magnets, but nothing for the sensors. However, on Fleabay I found sensor pig tails, but not sure if they would work.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
