Had to have ignition coil cylinder one replaced at 95K. Is this a common problem?
We now have 104K, and, often, we are not near home. One mechanic suggested replacing the remaining five coils prophylactically.
Interested in hearing what others have to say.
Additionally, is there anything else not included in normal maintenance one should address at this mileage?

 

Some owners just change coils and spark plugs at the same time. Others, wait for the first one to fail, and replace ALL of them, and others one at a time.

Replacing ALL of them by inexpensive coils beats the purpose of prophylaxis since being inexpensive and new does NOT mean they will work.

It is a judgement call. The common advice is to buy MB/OEM coils ONLY.

 

Thanx for your input. Greatly appreciated!

 

Do replace ALL [coils + boots] at once!

This failure suggest HIGH HEAT...

Now is a good time to catch the CPS leaking oil into harness.

Change engine oil sooner that factory interval: 5kMi.

 

I had a coil go out on my ML 350. At the suggestion of my Mechanic I replaced all coils and plugs. WOW what a difference in performance, I couldn't believe it.

 

I mentioned in this thread reply that one of the original ignition coils in my 2015 ML 350 with the M276 V6 gas/petrol engine (not FFV/ Flex Fuel/ E85 capable...those use different coil packs) didn't even make it to 90,000 miles. The previous owner had all of the spark plugs (but not the coils) replaced a little earlier at 52K miles at his local Mercedes-Benz dealership. For that model year, the manufacturer of the Genuine Mercedes OE ignition coils used for those engines was BERU (part of BorgWarner). As I have pointed out in a number of my comments and posts in recent years, it isn't uncommon for those original coils to start failing well before 100K miles. The latest revision of the Genuine Mercedes OE ignition coils are now manufactured by Bosch. I have discussed this with the service managers and techs at my area's independent Mercedes shops, whose Mercedes techs had all been Mercedes-Benz master mechanics at dealerships in the area, and my recommendation is to replace all of the ignition coils at the same time when the spark plugs are replaced at, or before, 100K miles, if the coils haven't already been replaced...and to replace them with the latest revision of the Genuine Mercedes OE (Bosch-manufactured) or the Bosch OEM ignition coils. During the recent pandemic, when supply chain issues abounded, there were periods during which the Genuine Mercedes and OEM Bosch ignition coils were on backorder (note that the OEM Bosch ignition coils still occasionally end up on backorder, and the Genuine Mercedes ones might be on special order from your dealership's parts department). Desperate owners noticed that the original coils had been manufactured by BERU and just ordered OEM BERU coils found at parts suppliers as replacements. Those newer OEM BERU coils often turned out to be far shorter-lived than the originals (sometimes failing within a year or so). Worse still, some went ahead and had non-OEM/aftermarket ignition coils installed and also experienced backfires that blew holes through their intake manifolds.

For reference, this is what the original Genuine Mercedes (manufactured by BERU) ignition coils look like for the M276 engine (not FFV/ Flex Fuel/ E85 capable):


...And these are the current Genuine Mercedes (manufactured by Bosch) ignition coils for the M276 engine (not FFV/ Flex Fuel/ E85 capable):

 

Check for coolant leaks around the plastic thermostat housing, radiator (inspect the corners), coolant lines, and plastic fitting at the firewall behind the engine. As the plastics age, they begin to develop cracks at around this age/mileage. It is common for owners who hadn't checked regularly for signs of coolant seepage in those areas to suddenly have those plastic parts burst open, causing a large amount of coolant to get dumped fairly rapidly. If that happens, it will strand you, of course. I am considering replacing the thermostat, a bunch of the plastic coolant lines, seals, expansion tank/reservoir, and that plastic fitting at the firewall as a preventative measure when I have my 100,000 mile service (including replacing the serpentine/accessory drive belt, tensioner, and idler pulleys) and coolant flush performed. ...And, as others in here mention, check for signs of oil seepage into the engine wiring harness from the camshaft position sensors (very common at that mileage) and camshaft adjuster magnets (far less common on the M276/M278 generation of engines than the previous one). If they haven't been replaced already, replace all of the camshaft position sensors with the latest revision. You can also get the camshaft adjuster magnet harness extensions ("sacrificial pigtail" extensions, as some in here call them) for the previous M272/M273 engines (they are compatible) from the dealership and have them installed at the connectors for peace of mind while you/your mechanic is in there. I have done that on my vehicle. There are also harness extensions available for the camshaft position sensors, but those are only available as aftermarket/non-OEM parts (easy to find on eBay...). I don't have any personal experience with them, but some members of the forum have had them installed, as well... Frankly, if you upgrade to the latest revision of the camshaft position sensors (there are differences in the plastic housing of the newest revision of sensors from the older ones), I'm not sure that you would also need the sacrificial harness extensions. Perhaps others can provide their experiences.