I'm hoping the upstream O2 sensor connectors for bank 2 just needs to be cleaned. The last shop mentioned one of the camshaft position sensors on bank 2 was leaking oil into the engine wiring harness, so I'm thinking oil might have made it's way down to the O2 sensor also.

Although I'd think they would've noticed that and did something about it when they swapped the new ones in...

Does anyone know if you need to remove any exhaust components to get to the upstream O2 sensors? The last shop claimed it was necessary, but I was able to find a video on a W204 C63 that showed them being pretty accessible after removing a cover.

I need to buy all the equipment for jacking up the car; hydraulic lift, jack stands, wheel chocks, and creeper. So I'd like to know what I'm getting into first. This might be the first and last time I ever use the stuff short of oil changes after everything I've had done now.

You'll need them for transmission services, the trans mount later, brakes etc, don't discount the value of tools when labor is $200/hr.

Sometimes unplugging and replugging an O2 sensor restarts it and gets it to start acting right. Just make sure you have a good seal is all. You said everything looked nominal earlier, I keep forgetting what info we "know". Usually if you swap the two sensors things go horribly wrong.

Yeah you probably have to uninstall the midpipe to make life easier to reach up for the fore O2 sensor, the aft one is easy. You might honestly just ask the shop if they can grab it for you cuz uhh all that stuff starts adding up if you think this is *THE* last item

Okay so I took it back to the last shop today and they swapped in another new bank 2 upstream O2 sensor. That cleared up the fault. Still have some hesitation events however. I was hoping they would clear up after letting the fuel trips re-adapt again. The drive home was stop-and-go for about 40 minutes probably averaging 35 mph... So I thought it might not be the best condition for adaptations.

Anyways, as I was getting close to home, my gauge cluster screen lit up red with a battery symbol... Shortly after, my infotainment screen shut itself off. Thankfully I wasn't far from home and I made it back with no issues. I left the car running and hooked up my scan tool to now see more new codes.

1337 - Communication with the starter or alternator has a malfunction.
0365 - The output for the actuation of the alternator has a malfunction.

I checked the alternator live data page and it seems to be sitting at the minimum of ~11V. Although curious it shows no electrical or mechanical fault with the alternator. ALTHOUGH, I do remember seeing an electrical fault on this page before with no error code just a few days ago when looking around at all the live data prior...

So it looks like I need a new alternator. Appointment booked to tomorrow morning. $1100 quoted for OEM alternator. 2 hours labor. Feeling hopeful somehow.

It's really curious how I all of a sudden got these codes. The electrical fault to the O2 sensor could make sense if the voltage was too low going to the sensor, but why just that one? And why after it had been replaced with new? Maybe the old one was just done for and not reporting properly?

And regarding the hesitation / lurching symptoms, bad voltage to any of the fuel mixture components could maybe cause this. But I'm out of my depth here so not sure.

you're making giant progress... low or unstable voltage do affect combustions.

You do see 11Volts and ECU report lost connection with ALT...

Can you see if your ALT is swamped by the timing cover oil leak? You may have to fix that leak.

A genuine $30 alt "regulator kit" may be enough or complete unit.

Let us know.

Timing cover leak? You mean the Crankshaft position sensor oil leak? That was resolved already.

I also came across just swapping the regulator but isn't it attached to the alternator itself? You'd still need to remove the alternator right? If that doesn't fix it, then you'd be looking at double the labor hours to then put a whole new alternator in retrospectively.

front timing covers are where the VVT Solenoids ("magnets") are attached. The silicone sealant fails to need replacement.

What your current mileage (low or high)?
If high then ALT bearings may benefit new unit
If low regulator alone should do.

88k miles. I had the Camshaft solenoids replaced on the right bank. The shop didn’t mention any oil seepage, it was just done preventatively due to the camshaft angle being off being previous logging. But yes I’ve seen that as a common issue…

> Recap...
you have a low mileage ALT that's failed without known cause.

(Disconnecting a healthy ALT_LIN gives the exact same ECU fault but then healthy ALT self-regulate 14.1V)

Your's stuck near 11V:
you could have bad pulley, bad diodes or bad regulator.

See if ALT is free wheeling or spinning with belt.

Can you read ALT data such as rotor RPM or nothing is coming through ?

DO charge up your flat battery.

I think I'm only able to see the alternator data shown in my screen shot. Which doesn't include ALT RPM. The screenshot doesn't show the electrical fault BUT I did look at this page yesterday where it did show an electrical fault.

Here's a video of the alternator spinning... Belt seems fine and it seems stable also. I also see no signs of oil seepage around the ALT. Also, when I cranked the car just now, the battery service message is gone. So hopefully it will allow me to drive to the shop that's a 30-40 min drive away tomorrow morning. If not, I have a portable battery-powered jump-starter/charger...

https://imgur.com/a/j8ADmdL

ALT DATA : "NO FAULTS" ?!?!?

That really means no COMS!
not a bad connector
not the bad pulley clutch
not bad rectifier diode bridge
but a regulator issue:
(loose screws or bad module)

Video shows a clean ALT, not oiled up.

Maybe you missed that I just saw it reporting an electrical fault yesterday. But yes it’s curious it wasn’t reporting a fault in the live data while the was an active code for an ALT failure.

I’d feel better about it being replaced entirely as it’s the same labor to just replace the regulator.

-- The ALT fields are unpopulated and seem to defaut as "No" despite ALT being unable to report.

-- It should really be shown as " - - - " for blank data.

-- That logic is misleading.

The ECU is smart enough to trigger a fault about non-responding ALT.

++++ BTW a new ALT may not entirely solve your original issue. I do hope it does!

You can look forward to dealing with stock voltage swings and hopefully not the yoyo drains.

90Amp yo-yo draining current may be what cooked your ALT.

It will be proven by new ALT output lower than 12.3V instead of 12.6V min.

One of the experimental swing fix involves... disconnecting the data link between ECU-ALT.

damn after all this and it was your alternator acting up?

well at least your maintenance is good to go for the next decade

it ain't over til it's over:
Let's see how stock voltage swings restore performance.

Just add to the evidence here, I found another thread where a user had the exact voltage issue and code: https://mbworld.org/forums/w212-amg/...d-insight.html

In short, they replaced the regulator and their issue came back a couple days later. Ended up needing to replace the entire alternator.

Parts cannon .... I'll wait to see if that new alternator helps anything - I certainly hope it does resolve it all. Once resolved I'll add this to the sticky:

"Bad alternator in m156 E63: causes misfires, hesitations, no initial CEL's"

And @ChrisHimself said, the only thing you haven't changed to make this car brand new is the windshield and the right rear taillight! (Oh and the glovebox lamp)

Unfortunately things have taken turn for the worse.

I attempted to drive it to the mechanic shop today but the battery had none of it.

When I started it up at first today, it started fine, but after idling for a few minutes, it started misfiring like crazy. Flashing CEL. I shut it off. Started it back up and it seemed happy after that. No CEL…

I thought it was well enough to drive to the shop. Nope. Made it about half way before everything electrical started shutting off… it went into 30 mph limp mode on the highway. I pulled it off the road and tried to kill it, but the engine would not stop. After about 5 minutes, it started revving and after another 5 minutes I hear a pop and smoke coming from the driver side engine bay…

Thankfully there was no fire. I’m thinking the car overheated from the fans stopping from dead battery (from the ALT not charging it)… And a hose blew or something. Quite a lot of fluid in the engine bay. And it looked like my car decided to take a wee all over the road.

After about 30 minutes waiting on the side of the road for a tow truck, I mustered the courage to check out the engine bay…. Greenish fluid. Coolant I think? Didn’t have much smell. Or it may have been the washer fluid? The top was on however and I didn’t see any culprits sticking out. Alternator seemed to be in one piece also…

Anyways, got it towed to the same previous shop so hoping whatever fluid busted open isn’t anything catastrophic or the fluid didn’t ruin anything electrical… Should know something by the end of the day.

Update after the shop has had some time to check it out:
The pop / vapor was the radiator. It busted open apparently. So currently looking at a new rad and new ALT. Could've been much worse I guess...

Also having them clear all electrical codes and recheck them for any possible residual electrical damage. And they're going to do a Block Test to verify head gasket integrity.

This is the most absolutely cursed car I have ever seen on MBWorld. Not to kick you while you're down but the green coolant is the wrong kind. I know its universal but the idea is the blue/pink/violet stuff lasts like a decade and is better for the environment.

Alternator is $1500 from me. I trust the chinese new builds over anything reman. TYC ftw
Radiator is about $400-ish in parts and 2hrs fan comes out so thats another $800 ish with a fresh pour
Hoses can be re-used but you'll need new o-rings for them at the minimum.

I'm using a Denso in my W212, love it. It was like $120 on Rockauto

Denso $120 vs. Bosch $1500
They're missing a zero


It's nice move from Germans leaders to setup Japanese partners as top notch. Great team work.

I wonder if you begun with a fully charged battery ??

This is nothing major. It will be good.

old turquois-blue can look light-green... as long as new coolant does not look straight green!!
I've had dealer play that then say: "who cares?"

The shop quoted me $1350 for the new Rad and everything involved. Obviously new coolant too.

$1100 for the alternator job. Bosch alternator.

Yeah probably not. I was in a rush and running on 4 hours of sleep so wasn’t thinking clearly before I left this morning…

Trying to view this in a positive light. It seems like the Radiator was a weak point considering it gave way instead of the head gasket (presumably).

Your exactly right on that one: the light crimps serve a purpose - It let's go to preserve the engine for another day. The ultimates are timing cover mayo seals.

Take it one step at a time with patience.

Something was lost in translation. Why did the radiator "blow"?

I’m thinking because the coolant was boiling from the engine overheating? The battery was dying completely with it not getting charged from the alternator. It was already a warm day here and I was halfway through my drive.

All the electronics started shutting off but I could not stop the engine. Once I stopped the car, the engine started revving on its own (bad voltage to the ECU maybe?). That, in combination with the radiator fan probably stopped. Radiator go boom!

But in all reality, it must’ve just busted open at a weak point rather than the entire radiator literally exploding into pieces…