dreaded oil in ECU?!?!
Thread Starter
Newbie
Joined: Sep 2014
Posts: 13
Likes: 0
W212 2012 E350 wagon
dreaded oil in ECU?!?!
🙏🙏Hi guys! I replaced my beloved W210 wagon with a newish w212 wagon (100K miles). I've experienced a slight engine hesitation "misfire" that occurs intermittently under light engine load / driving up gradients. It's usually hardly noticeable, but more pronounced in occurrence / severity in warm temps (80f plus). I can usually trigger it by increasing throttle from 1800-2000 rpm / 70mph up a slight incline on the highway. Engine will slightly "buck", increasing throttle a bit more will stop symptom. Otherwise car ran flawless. I changed spark plugs & coils w/ oem parts, good times!! Is it just an afterthought from engineers that you might have to service this car someday lol !?!? Anyways, no change in symptom. Sidenote: Upon plug/coil install, I noted scant oil in the air intake assembly around throttle body. I cleaned it up, not much new oil occured there in 7K miles. I understand this is not ideal, but tolerated w/ this engines PCV design. I see a catch can install in the future. I also had the transmission serviced for giggles, again no change. Lately, this "misfire" became more pronounced as weather got hotter, so I decided to address the cam position solenoids & position sensors. I had noted slight oil around those units a year ago. I ordered the sacrificial pigtail kit w/ sensors from FCP euro, hoping maybe this was my "misfire" issue. I was only able to replace the passenger side solenoids, sensors, and pigtails. Driver side had to wait due to intake manifold removal required / new intake gaskets. When I unplugged cam position sensors, both had significant oil noted in connections (no oil noted in solenoid cam sensor connection). Cleaned them out w/ the kits provided electronics specific cleaner spray. Allowed to airdry / hit w/ air gun. I assessed electrical connections downstream from noted oil in sensors, and found damp shiny residue in the ECU connection. Despite my instincts, I sprayed provided electrical cleaner in female ports & ECU male ports while upside down & allowed them to drip face down. Air gunned them prior to reconnect. On test drive post battery reconnect, I threw about 10 codes (P2088,0010,0300,0301,0303,0302,0113,0098,0108,213 7) & car quickly went into limp mode. YIPEEEEE!! I have assumed I introduced oil into the harness connection, possibly inside, the ECU. It was likely there already, but I may have forced it to new critical places? I have soaked the the connections in 91% alcohol, tried various electronic cleaning sprays & ensured more airdry time w/ fans etc. No change except for new codes. I haven't opened the ECU, but do anticipate sending it off to be assessed / tested (recommendations for referral?). Sorry about the LONG thread, wanted to be thorough. I'm trying to trouble shoot & reduce my impending mechanic / shop bill. THANK YOU VERY MUCH for your time!!!!
Out Of Control!!
Joined: Apr 2019
Posts: 11,922
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
OIL LEAK 10K-HARNESS
🙏🙏Hi guys! I replaced my beloved W210 wagon with a newish w212 wagon (100K miles). I've experienced a slight engine hesitation "misfire" that occurs intermittently under light engine load / driving up gradients. It's usually hardly noticeable, but more pronounced in occurrence / severity in warm temps (80f plus). I can usually trigger it by increasing throttle from 1800-2000 rpm / 70mph up a slight incline on the highway. Engine will slightly "buck", increasing throttle a bit more will stop symptom. Otherwise car ran flawless. I changed spark plugs & coils w/ oem parts, good times!! Is it just an afterthought from engineers that you might have to service this car someday lol !?!? Anyways, no change in symptom. Sidenote: Upon plug/coil install, I noted scant oil in the air intake assembly around throttle body. I cleaned it up, not much new oil occured there in 7K miles. I understand this is not ideal, but tolerated w/ this engines PCV design. I see a catch can install in the future. I also had the transmission serviced for giggles, again no change. Lately, this "misfire" became more pronounced as weather got hotter, so I decided to address the cam position solenoids & position sensors. I had noted slight oil around those units a year ago. I ordered the sacrificial pigtail kit w/ sensors from FCP euro, hoping maybe this was my "misfire" issue. I was only able to replace the passenger side solenoids, sensors, and pigtails. Driver side had to wait due to intake manifold removal required / new intake gaskets. When I unplugged cam position sensors, both had significant oil noted in connections (no oil noted in solenoid cam sensor connection). Cleaned them out w/ the kits provided electronics specific cleaner spray. Allowed to airdry / hit w/ air gun. I assessed electrical connections downstream from noted oil in sensors, and found damp shiny residue in the ECU connection. Despite my instincts, I sprayed provided electrical cleaner in female ports & ECU male ports while upside down & allowed them to drip face down. Air gunned them prior to reconnect. On test drive post battery reconnect, I threw about 10 codes (P2088,0010,0300,0301,0303,0302,0113,0098,0108,213 7) & car quickly went into limp mode. YIPEEEEE!! I have assumed I introduced oil into the harness connection, possibly inside, the ECU. It was likely there already, but I may have forced it to new critical places? I have soaked the the connections in 91% alcohol, tried various electronic cleaning sprays & ensured more airdry time w/ fans etc. No change except for new codes. I haven't opened the ECU, but do anticipate sending it off to be assessed / tested (recommendations for referral?). Sorry about the LONG thread, wanted to be thorough. I'm trying to trouble shoot & reduce my impending mechanic / shop bill. THANK YOU VERY MUCH for your time!!!!
Can you pls decipher the trouble codes you're interested in with what status: "stored/active" ?
BTW did you disconnect your AUX Batt when MAIN was Off ????
Last edited by CaliBenzDriver; Jul 1, 2025 at 02:58 PM.
Thread Starter
Newbie
Joined: Sep 2014
Posts: 13
Likes: 0
W212 2012 E350 wagon
Thks for responding! I did not disconnect the aux battery, hope that didn't contribute to this situation. The codes are noted in original post from initial scanner reading (P2088,0010,0300,0301,0303,0302,0113,0098,0108,2137 ). When I tinkered w/ car today & started it, it had a bad camshaft adjuster rattle that went away after a couple seconds. I'm assuming this is due to improper / no info going through computer to cam solenoid? Kinda concerned Im in danger of causing mechanical damage to engine now. Appreciate the help
Thread Starter
Newbie
Joined: Sep 2014
Posts: 13
Likes: 0
W212 2012 E350 wagon
Per my scanner, codes are not permanent. I clear them, unhook battery, scan to confirm still clean, start car & it throws codes again & goes into limp mode. Most recent engine start resulted in loud rattle from cam adjuster. Guess cam solenoid is receiving wrong / no signal maybe? Concerned I'm gonna cause mechanical damage etc.
Out Of Control!!
Joined: Apr 2019
Posts: 11,922
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
more fault info
Thks for responding!
I did not disconnect the aux battery, hope that didn't contribute to this situation.
The codes are noted in original post from initial scanner reading (P2088,0010,0300,0301,0303,0302,0113,0098,0108,2137 ).
When I tinkered w/ car today & started it, it had a bad camshaft adjuster rattle that went away after a couple seconds. I'm assuming this is due to improper / no info going through computer to cam solenoid?
Kinda concerned Im in danger of causing mechanical damage to engine now. Appreciate the help
I did not disconnect the aux battery, hope that didn't contribute to this situation.
The codes are noted in original post from initial scanner reading (P2088,0010,0300,0301,0303,0302,0113,0098,0108,2137 ).
When I tinkered w/ car today & started it, it had a bad camshaft adjuster rattle that went away after a couple seconds. I'm assuming this is due to improper / no info going through computer to cam solenoid?
Kinda concerned Im in danger of causing mechanical damage to engine now. Appreciate the help
your "startup rattle" is existing mechanical defect of intake VVT.
Do repair the rattle ASAP before it turns into "correlation faults" them you'll need camshafts replaced.
Camshaft positioning solenoid have nothing to do with startup rattle. It's caused by unlocked VVT gear(s) worned out by stock limited oil pressure.
Last edited by CaliBenzDriver; Jul 1, 2025 at 07:21 PM.
Thread Starter
Newbie
Joined: Sep 2014
Posts: 13
Likes: 0
W212 2012 E350 wagon
OK. I'm aware of VVT issue w/ these engines. I have noted very mild valve "chatter" on start up / especially cold days. But never this pronounced. Just figured it tied into my related cam sensor codes & suspect electrical issues.I feel like I need to address electrical connection prior to chasing down the mechanical cam VVT potential issue. Tempted to send off ECU to a specialist to assess if its compromised / oil inside.thks again
Out Of Control!!
Joined: Apr 2019
Posts: 11,922
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
OK. I'm aware of VVT issue w/ these engines. I have noted very mild valve "chatter" on start up / especially cold days. But never this pronounced.
Just figured it tied into my related cam sensor codes & suspect electrical issues.I feel like I need to address electrical connection prior to chasing down the mechanical cam VVT potential issue. Tempted to send off ECU to a specialist to assess if its compromised / oil inside.thks again
Just figured it tied into my related cam sensor codes & suspect electrical issues.I feel like I need to address electrical connection prior to chasing down the mechanical cam VVT potential issue. Tempted to send off ECU to a specialist to assess if its compromised / oil inside.thks again
--1-- if you decide to get your ECU repaired then you will want to install an oil-free harness.
--2-- The rattling will need troubleshooting to survey damages: tensioner, intake VVT, camshaft
Last edited by CaliBenzDriver; Jul 2, 2025 at 03:07 AM.
Trending Topics
Junior Member
Joined: Feb 2011
Posts: 31
Likes: 2
From: Miami FL
2010 E350
thanks!
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Out Of Control!!
Joined: Apr 2019
Posts: 11,922
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Junior Member
Joined: Feb 2011
Posts: 31
Likes: 2
From: Miami FL
2010 E350
