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Hello, I have recently been having issues with my E class. I took it to an Indy mechanic and these are the codes that are showing when they run their scanners. The car would drive fine but be sluggish sometimes throughout shifting and I would often have to turn it off and on to get it back to normal. Additionally in the 2nd to last picture the trans cooler line is dripping fluid. I know it’s already getting diagnosed at the mechanic but any input on this would be greatly appreciated. Also fwiw the spark plugs were recently replaced.
Well, now you know what a 3 Cyl. misfiring feels like.
Fuses down just blow up... scrutinize how the sparkplug replacement job was performed.
More fuses won't repair what is shorting out.
Last edited by CaliBenzDriver; Feb 28, 2025 at 01:54 AM.
Yes. The prior mechanic probably wasn’t the best to replace the spark plugs. But I will let them know tomorrow about the ECU. The prior mechanic said there was some residual oil off the connector that goes into the ECU. After some extensive research on this forum I see that worse case scenario this could be a call to replace the engine wiring harness but it makes me think what would stop this from happening again even after the harness is replaced. Thanks for your help guys!
Yes. The prior mechanic probably wasn’t the best to replace the spark plugs. I will let them know tomorrow about the ECU.
The prior mechanic said there was some residual oil off the connector that goes into the ECU.
After some extensive research on this forum I see that worse case scenario this could be a call to replace the engine wiring harness but it makes me think what would stop this from happening again even after the harness is replaced.
Thanks for your help guys!
Good thinking! How to stop oil contaminating the engine harness to ECU?
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Was the yellow screenshot your car? It says the ECU MED177 is for an M278, used in the E550, not E350. It should say "Motor electronics 'MED177' for combustion engine 'M276' (ME)". However, maybe that's just a quirk of that scan tool. The part number does show 276 901, though your actual engine part is 276.952, as shown on the Snap-On tool. The reason I mention all of this is the scan tool used in the first pic should be up to date and accurate. If not, it can give you false readings and a rabbit hole to go down. By the way, all of those codes are STORED and not CURRENT, meaning they should clear and were probably caused when the spark plugs were changed.
Changing plugs on your engine is a pain-in-the-*** (compared to the M276.8XX bi-turbo engines) because the intake manifold must be removed to do it right. (There will be folks who say you can replace the plugs without removing the manifold, but that's not the factory approved method. One thing I have learned is that the factory approved method is usually the safest and most efficient way to do things.)
Look at your invoice. What parts were used? Those green sealing rings should be replaced. If they get messed up and don't seal properly, you could get misfires -- too much air. Look for part number 2761410180.
Last edited by JettaRed; Feb 28, 2025 at 08:59 AM.
On M276.9xx fuse 23 does more than just powering COP coils. Attached 2 wiring diagram.
Fuse 23 ------> It serves Z7/38z1 splice and then shared by 7 components
On M276.9xx fuse 23 does more than just powering COP coils. Attached 2 wiring diagram.
Fuse 23 ------> It serves Z7/38z1 splice and then shared by 7 components
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So, do not assume that COPs are the only suspect.
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I got it fixed guys! After a stressful few days new coil packs and spark plugs she’s back up and running like new. Going to do some preventative maintenance as well when I’m back in the U.S.
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