Hey guys, I recently made a post about the CEL codes that came up around the time that a rock went through my radiator: codes P026E and P2CB0. This is a 2020 E63S with 2,000 miles.

I saw a puddle of coolant and upon further inspection found a rock that went through the bottom part of the central radiator. I took the car to a shop that quoted me $1100 to replace the radiator which I was glad to pay.

The car was returned to me today but I was told the CEL was still coming on. I have to bring the car to MB anyways for a Bluetooth issue (I didn’t have the radiator replaced at a dealership but rather a high end shop) so I figured I’d just have them take a look because I thought the CEL would just take a few cycles to clear. Apparently one of the two codes has to do with the coolant but that might not be accurate.

I drive off the shop with the CEL not showing up. Later on in the drive, it comes back on. Then I realize the transmission temperature is going up. At this point I’m starting to absolutely freak out because the radiator was repaired but clearly something else isn’t right. They want me to bring the car back to the shop tomorrow to check the intercooler and the transmission fans, but they said it was very unlikely that a rock would be able to screw up the transmission fans and they saw nothing wrong with the intercooler.

I’m really concerned because it’s a brand new car, I just had a rock go through the radiator due to MB’s poor design of the grille, and clearly even with a brand new OEM radiator the car is still overheating. I want to have an idea of what could be the culprit before taking it into Mercedes where I know they’ll blindly poke around for a week before finding something.

See below image where you see CEL and transmission temp through the roof. Help please

 

You have another issue that is not the radiator. I'd suspect a pump or relay.

 

Why not just let the dealer take care of it? It's a brand new car.

 

The dealer or anyone with a Xentry, you can easily test all 3 electric pumps, and even run the bleed procedure.
It just seems most techs dont understand how this system works nor how to use their own dealer software.

 

Well I replaced the radiator at a shop instead of the dealer because A) the radiator wasn’t going to be covered under warranty, B) last time this happened to me, Mercedes charged me double what an independent shop would charge me, and C) Mercedes would take much longer to diagnose and repair the car from my experience.
Because these guys replaced the radiator I decided to take it back to them before Mercedes to have them since they might just be able to fix it. If it needs further repairs that would be covered under warranty, I’ll obviously take it to the dealer.
They found some air in the coolant lines which is being drained, looking to see if there’s anything else that could be wrong. Will keep this thread up to date

 

This is a big reason as to why I didn’t go to MB first. I never feel confident. Sometimes I’ve brought a car in knowing exactly what’s wrong and they would kind of brush it off like I don’t know what I’m talking about and proceed to spend 3 days poking around to find out what’s wrong with the car, only to tell me what I already knew (or, worse, try to tell me the car needs something it doesn’t - like when I needed brake pads but they tried to force me to replace rotors that were in ok shape).

Granted, my decision to repair my car at an independent shop didn’t fix the problem. But it’s hard to say if the additional issue was just not identified at first or if it was due to neglect from the shop. I doubt the latter. They’re bleeding out the air and hopefully that should suffice, they don’t seem to think that there’s a major issue with the car. They think the radiator was the culprit and whatever is causing the overheating is something stupid. Fingers crossed.

 

Excellent, Well now you have some knowledge for help, tell your shop they can access a bleed procedure electronically to help bleed out the air from the entire IC/Trans cooler system on top of doing it the old fashion way physically. Usually those good aftermarket scanners can run these procedures aswell and activate the electronic pumps to make sure they are working. The cooling system has more components than the usual system, but it is pretty simple.

 

As it turns out, one of the radiator hoses was pinched. They said they rectified the issue and just have to bleed the air from the coolant lines. There was some air in it as well from when I brought the car back in.

I pick up the car tomorrow. Hopefully that’s all that was needed to fix.

 

It’s not looking good... they found a pinched hose so coolant wasn’t flowing. They fixed it and bled the coolant lines multiple times but still the transmission is overheating. There are no holes, no leaks, no electrical issues, no air in the coolant lines. Coolant temperature is good, engine oil is good, transmission is overheating. Pumps are working as they should. They don’t know what’s wrong with the car and need me to take it to Mercedes at this point. This is really starting to become a mystery. The car will be dropped off at a dealership and I’m hoping that as such the car will be properly diagnosed. Any suggestions greatly appreciated.

 

It's weird that a radiator hose would be pinched to the point that no coolant could flow through. Did the shop messed up while replacing the radiator? The overheating even after radiator replacement could possibly mean the tranny was probably damaged when it first overheated. Best of luck!

 

There is only a few things it can be. Are you IAT's also high?
If your shop has access to Xentry software, not only can you activate the pumps to see if they are working, you can keep an eye on them to make sure they are coming on when they should be while you are driving and at what % they are kicking in on.
On top of this, you can also see if the Trans switchover valve is open. If this stays closed, then the trans will not get cooling.
I would also run the electronic bleed procedure a few times, sometimes doing it once doesnt do the job.

P.s. Stock CPC?

 

Not sure if the shop is to blame for the hose. I give them the benefit of the doubt, but who knows. I don’t think the tranny is damaged, and they don’t either. It’s not shifting weird at all, first and foremost. These transmissions can take a rough beating before anything bad happens. My C63 tranny was cooking at 280 degrees and after radiator was replaced it was good as new. Also this car hasn’t been pushed at all. Followed break in procedure and barely any spirited driving.

 

Sorry not familiar with the term IAT. Intake air temp? Nothing is overheating except for the transmission.
The shop doesn’t have Xentry, which is probably why they can’t diagnose it. The dealer will be looking at it tomorrow. Thankfully it’s been cold out so I have time to drive to dealership for example before the transmission overheats.

And yes. The car is 100% stock, nothing has been done to it thankfully.

 

Mines been doing this pretty much since I've had it 3 services last one major including trans oil change still they cant find what's wrong with it as mentioned they are idiots I've even told them what to look for pointed out on here on a number of occasions i think they just cant be bothered!

 

Wow, one part of me is glad someone else is going through something similar but I also hate to see that you haven't been able to get it fixed. Are you getting any CEL codes? If so, which codes are you getting? They started working on the car already, I should have some information on the car tomorrow.

 

no codes have ever come up! I will take to a Mercedes specialist with the correct software to check all that’s been mentioned on this thread at least I can ask them to do all the correct checks!

 

How hot is your transmission temperature getting? Yes, if you can look into it for your car and let us know if they find anything that would be great. I really am confused at this point, the first place I took it to said there are no leaks and no pump issues or anything like it but they aren't specialized in Mercedes so I think they may have missed something. The service manager thinks they should have a better idea of what's going on with the car by tomorrow afternoon, so I'll fill everyone in by then. From what I understand, there are only a handful of things that can possibly cause the transmission temperature to be so high, so if we put this in front of the right shop foreman it won't be rocket science.

 

Been in the red a few times telling me to pull over but its doesn't drop the fans are blowing flat out! could be a sensor or a pump maybe we will see! most service managers at Mercedes in the UK are ****e and in general Mercedes after care service is also ****e but love the AMG's had for years now so have to put up with the poor aftercare service!! Watch this space! if its any consolation its not an uncommon fault there are numerus threads on here regarding the same issues with different outcomes

 

That's crazy, I don't drive the car after it passes 220-240F because that temp can start to do damage to the transmission. It's definitely scary to see the trans temp in the red. But is this something that happens every now and again? For me ever since this started it's happened every time I've driven the car and the CEL codes make it impossible to ignore.
I took the car to arguably the best Mercedes dealer for both sales and service in my area. The ones I've gone to in the past have been horrible so I feel better going out of my way a bit to leave the car somewhere that I think it would be in better hands. I'm confident that there's something wrong with the pumps or perhaps a sensor that the shop that originally inspected the car simply didn't catch. This really can't be a mystery. Will keep everyone posted.

 

Update: coolant recirculating pump was found to be faulty, it's being replaced and should get the car back soon.

 

that's great news.

 

I really need to open my own shop.

 

Yep great news! well done also to the knowledge from this forum👍👍

 

Hey guys, I was really hoping I would never have to write on this thread again but the reality is different.

I picked the car back up after the coolant recirculating pump was replaced. The next day, I was parked with the engine running waiting to pick someone up when this loud, whining noise came about. I thought I was parked near some kind of machinery of sorts that was making noise, so I reversed the car to see if the noise would go away. It didn't. ****. I started to realize this is coming from the car. I turned the car off, the sound kept happening. It kind of sounded like the horn, so I pressed the horn and the horn worked just fine.

Here's a link to a video where you can hear the sound: https://www.youtube.com/watch?v=U-bk...ature=youtu.be

At that point, the transmission wasn't overheating or anything. It was just making this very annoying and bizarre sound. It happened a couple of times that night and went away. The next day, it happened again at night, albeit for a much shorter period of time. The guys at Mercedes don't really know what it could be, they thought it could be the horn but there's no way. They also thought maybe it's an air bubble in the coolant line. I did some googling, and the results say it could be a loose fan belt or low on transmission fluid. I don't know how accurate these websites can be, especially for a 2020 E63 with brand new mileage, but that's what I'm working with.

A day later, I'm driving the car just fine all day. Towards the evening, I notice the transmission temperature start going up. It reached 240F at one point, but by then I had gotten to my destination and shut the car off. Maybe an hour later I turn the car on only to see the beautiful CEL beaming in my face. Amazing! Jesus Christ this is getting ridiculous.

I just dropped the car off at the dealer again. They're doing everything they can to speed up the process and have the car checked out ASAP so I have the least downtime. They're doing the most they can which I really appreciate, but I really don't understand what else can be the culprit at this point. As always any advice would be appreciated.

 

Jesus!! Mine does something very similar so must be something to do with the trans cooling! no CEL on mine though and been into Mercedes! let me know what they say! mine does it now and again bit random so unless it throws an error code they cant find out why look forward to what they say it could be!!

PS googling sometimes makes things worse same as if your feeling ill eventually is says your going to die regardless of what actually is wrong with you!! round and round in circle's chasing your tail!