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Before I have my wagon towed to the dealer…. Need help!
Hey everyone, I'm looking for some advice on my 2011 E350 4MATIC (M272 engine). I've been dealing with a tough set of issues and would love to hear if anyone else has had a similar experience.
Current symptoms:
Persistent check engine light, with a P0304 (cylinder 4 misfire).
ABS and transmission stuck in Park—no gear shift possible.
Various CAN bus communication faults: N73 (EZS) and ISM control unit errors (codes 475300, 475A00, 631E00,
I want to add that a few days prior to the no shifting issue, I had replaced the auxiliary battery due to the fact that my vehicle was randomly shutting off at most speeds when parking or backing out of a parking space. There were even times of the vehicle was in motion that the engine wanted to cut off.
Even after the NO SHIFT warning appeared, the vehicle starts up just fine, and the steering wheel turns as well, but I can’t shift. I have replaced all the spark plugs and ignition coil on cylinder four and also swapped newer with a known good one, but still the issue of misfire persist. I was told by an MB technician that he thought my in intake manifold plunger had failed, so I’m thinking that maybe the reason for the misfire, but I’m not sure
I know this is a lot to digest.I need directions on what to check next would be greatly appreciated.
AUTOZONE OBDII SCAN AUTOZONE OBDII SCAN AUTOZONE OBDII SCAN Swapped these relays in front fuse box
The manifold is not an uncommon thing...after many miles or years. Yours is a 2011..so it at least has years. I can not see how that would alter your shifting or give you a "do not put the car into gear" warning. I assume you have the ability to look at live data with the engine running - more over, see if #4 is getting any spark at all. Would be neat to take coil off, ground out another plug and see if there is a spark in the gap.
The manifold is not an uncommon thing...after many miles or years. Yours is a 2011..so it at least has years. I can not see how that would alter your shifting or give you a "do not put the car into gear" warning. I assume you have the ability to look at live data with the engine running - more over, see if #4 is getting any spark at all. Would be neat to take coil off, ground out another plug and see if there is a spark in the gap.
I know that the intake manifold is not the reason for the vehicle not shifting, but would like to get it handled, regardless. I was thinking about going with the repair kit as opposed to replacing the entire unit. I wouldn’t be doing the repair but would have a technician friend of mine do it who works at a Mercedes dealership.
I’m really praying that this is a wiring or ground issue as the EIS and ISM both started throwing codes around the same time so either I’m very unlucky or something else besides those units is the culprit.
When my E would not shift...it was a NOT CHEAP controller that was on the transmission. Car had to be towed...it was a thing.
As for the rebuild kit for the top end - I have heard from more than one person that it is just easier to buy the new one. A guy I know (very good mechanic) got frustrated with rebuilding his (on and off a few times) and finally - seriously threw it across the garage and got the unit as a whole (as in the link). There are a few cheaper sites...but the FCP is complete....(I have to put one of those onto one of my cars).
If that’s the case, I may just go with a new throttle body assembly. Especially since it comes with the metal rods.
Was your transmission issue due to the ISM or DSM? I may end up just having it towed to the dealer since Mercedes will pay for the tow and I have connections there from when I was a service advisor.
ECU: the engine No4 missfire does not appear to be the top issue today.
EIS/EZS: keyslot module appear to be seriously disrupted, that's all. Check ESL activity also.
ISM: tranny PRND shifter can stay put for this time.
Chassis voltage appears reasonable at 14Volts.
> Fault SCANNER Consideration...
You've pulled relays and fuses that may have STORED new faults in a number of good modules.
An ACTIVE status is required for fault consideration (some stored faults are really live transients)
Not having a scanner is going to require use of local professional services.
As a former MB Sce Adviser you can already write your service slip.
You car really need to be diagnosed first, specially the misfires. Based on your steps we can already guess it's not ignition, perhaps injector.
> Next time...
Do buy a scanner to help you see disruptions maturing into the snowball you are facing now.
Don't pull anything out of a powered SAM.
Be proactive with misc services:
+ Engine oil +
+ Brake flush +
+ 4Matic +
+ Cooling system +
+ air/cabin filters +
Last edited by CaliBenzDriver; Mar 2, 2026 at 02:37 PM.
ECU: the engine No4 missfire does not appear to be the top issue today.
EIS/EZS: keyslot module appear to be seriously disrupted, that's all. Check ESL status also.
ISM: tranny shifter can stay put for this time.
> Fault SCANNER Consideration...
You've pulled relays and fuses that may have STORED these faults in a number of good modules.
An ACTIVE status is required for fault consideration (some stored faults are really live transients)
Not having a scanner is going to require use of local professional services.
As a former MB Sce Adviser you can already write your service slip.
You car really need to be diagnosed first, specially the misfires. Based on your steps we can already guess it's not ignition, perhaps injector.
> Next time...
buy a scanner to help you see disruptions maturing.
thank you, Cali Benz. I appreciate the input. And yes, I do need a good scanner. I have one, but it’s very limited in its abilities.
I also agree that the misfire is of less importance as the engine does seem to run well. I’ve done my best take as good care of this vehicle as I can and stay on top of all the preventative maintenance items. Although I’ll admit, wiring and electrical is not my strong suit.
We almost never saw vehicles with this age at the dealership when I worked there, so I rarely ran into any issue like this.
Which scanner do you suggest for Mercedes actually pinpoint individual modules and not just generic codes like most?
thank you, Cali Benz. I appreciate the input. And yes, I do need a good scanner. I have one, but it’s very limited in its abilities.
I also agree that the misfire is of less importance as the engine does seem to run well. I’ve done my best take as good care of this vehicle as I can and stay on top of all the preventative maintenance items. Although I’ll admit, wiring and electrical is not my strong suit.
We almost never saw vehicles with this age at the dealership when I worked there, so I rarely ran into any issue like this.
Which scanner do you suggest for Mercedes actually pinpoint individual modules and not just generic codes like most?
The scanner of choice is "LAUNCH cReader Elite" around $130.
It has 100% comprehensive coverage
It has fault descriptions
It has pdf reporting
It gas live data
There are many better scanners tablets and dongles.
The key is the coverage of W212 era, not the latest models with security tokens.
Technician is going to clear current faults to see which are first to return.
EIS' a serious gem that showcase solderless pins.
Last edited by CaliBenzDriver; Mar 2, 2026 at 03:44 PM.
yes, get the latest in that price range... 2.0. This is a very capable unit.
I just ordered and I’ll have it later today
I wanted to add that I’ve only use the keyless go button with this vehicle and never actually turned the key except when we were setting the service interval. Would my EIS still have the soldering issues?
I wanted to add that I’ve only use the keyless go button with this vehicle and never actually turned the key except when we were setting the service interval. Would my EIS still have the soldering issues?
yes, it's built to great standards with everything necessary to require factory trained repair or 5mn quick soldering.
Last edited by CaliBenzDriver; Mar 3, 2026 at 03:02 AM.
The hard part to harvest the module is done, now the soldering ...
couple screws to access the special pins of interest
Show us the circuit board if you can
Work on top of a clean newspaper the module has two board sandwiched if my memory serves me
after a short night flying over to sunny Miami. beautiful Caribbean sashimi 😋
This module includes a couple optical sensors we are going to clean while in there.
solder loose pins
clean dust
reassemble module
reinstall module
power up chassis batteries
clear live faults
Good time well spent?
PLAN B... fresh genuine parts
Last edited by CaliBenzDriver; Mar 3, 2026 at 07:47 AM.
The hard part to harvest the module is done, now the soldering ...
couple screws to access the special pins of interest
Show us the circuit board if you can
Work on top of a clean newspaper the module has two board sandwiched if my memory serves me
after a short night flying over to sunny Miami. beautiful Caribbean sashimi 😋
This module includes a couple optical sensors we are going to clean while in there.
solder loose pins
clean dust
reassemble module
reinstall module
power up chassis batteries
clear live faults
Good time well spent?
PLAN B... fresh genuine parts
Thank God harvesting was the hardest part, because it was an absolute nightmare getting it out of there. Having only one fully-functional hand didn’t help either, and it was my nondominant hand at that. I had my right index finger knuckle fused last Friday, hence why I’ve been off work.
one thing to mention though… I’ve never soldered anything in my life. I’m thinking about finding someone at the shop or possibly finding a person on NextDoor that knows what they’re doing. Disassembling and cleaning shouldn’t be an issue.
Wipe the optical sensor gently a bit so you don't create static on the plastic to attract... dust!
i’m sure the board comes off the black plastic piece but I’m a little nervous about disconnecting the two and possibly breaking something but here are two pictures…
detail of the 3-pins used to run the dual RF coils (this don't need particular attention)
soldering assignment in 3 groups
If you want to keep it quick, don't remove the circuit board from the trst of the lock. Solder pins from the
top side... solder will fill the gap and make good connections.
Last step is to make sure, soldering pins did not create any unintended solder bidges.
Lets see an after picture...
Thats all there is to this EIS module!
Next installement : KGo module festures 3 times more loose pins.
Last edited by CaliBenzDriver; Mar 3, 2026 at 09:49 PM.
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