While I wait for the tow truck: P1523
I was driving on the freeway at 60-65mph (seriously, it's very busy today) for about 25 minutes. The check engine yellow symbol lit up but with no other messages or obvious issues. As the road is being worked on, there are no shoulders, so I continued, to the next exit a few miles ahead. After a couple of minutes, I saw that the turbo boost gauge was pinned to Max, even with very light throttle. I got off the freeway and shut the car down and locked it for ten minutes to see if it would reset.
On restart, the check engine symbol was still on, but throttle response and the turbo boost gauge were normal, so I headed home, just 10 minutes way. Two minutes from home, the turbo boost gauge maxed out again at very light throttle opening. My OBD II reader reports code P1523, which may include the Throttle Actuation Control, but seems to point at multiple potential issues. A faulty TAC could be correlated with the max boost indication. The car is being flat bedded to my dealer this afternoon, but I'm wondering is anyone else has experienced this issue. I've only owned the car for a month, but its codes haven't been reset since new, so this is a new issue for it.




You can really help them by narrowing down when this bug shows up:
- cold/hot engine
- fast/slow driving road
- short trip/long trip
Hopefully your issue will get worked on by an Ace tech sooner than later.
Good thing you already know about the shut-off+ lock reset.
Another personal favorite is "whole car Reboot" by disconnecting batteries. This effectively resets the SAM's.
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You can really help them by narrowing down when this bug shows up:
- cold/hot engine
- fast/slow driving road
- short trip/long trip
Hopefully your issue will get worked on by an Ace tech sooner than later.
Good thing you already know about the shut-off+ lock reset.
Another personal favorite is "whole car Reboot" by disconnecting batteries. This effectively resets the SAM's.
🤞




Many other folks will be interested to learn.
Thank you,
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They’ve seen this on other cars: sometimes it’s turbo exhaust clamp issues, but not always. Nice to know that they and the dealer are on the case.
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I drove the car home in 25 miles of heavy evening traffic. All seemed well, until, not far from home: after a stop, I gave it some gas and the car accelerated normally to about 45mph. However, right after that, I noticed that the turbo boost gauge was maxing out on light throttle. I'm new to the car, so I don't know if it's normal for the ECM to keep the turbos spun up after some heavy(ish) acceleration. As I slowed down for my driveway, the turbo gauge rose to about 80% of max on each downshift. If this is normal behavior, all is good. But, if not, then it's back to the dealer I go.
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The way your issue is already escalated to a German support engineer is very promising.
See if the problem resets itself for a while with a simple Ignition cycle (On/Off/On)
-Or if it continues until the car gets reset by the dealership.
If you have your own code scanner... indulge into scans for a glance at what's going on...
Intermittent glitches are never easy to pin point.
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Last edited by FlyingBear; Sep 22, 2022 at 08:12 PM.




All codes were cleared by my dealer before releasing the car to me. I guess that means that the glitch is still there but hasn’t happened enough to trigger an alert.
An hour in heavy traffic on am 87 degree day got the underhood environment good and hot, for sure.
Already the righting is on the wall, you know it, we know it but don't necessarily let the dealer know that or they'll start pointing fingers at you instead of fixing your automobile.
The root cause of P1523 was not immediately clear to the brilliant support engineers. In the end they will work out this factory defect given some time.




Helping them to reproduce the conditions will shorten the race to a solution.
Last edited by CaliBenzDriver; Sep 24, 2022 at 12:30 AM.
However, after hooking the car up to the Xentry system, it verified the P1523 stored code, with an explanation that an evap system flap was stuck open. The dealer is ordering parts for various check valves to replace them.
I have nothing but positive things to say about the dealer. While I bought my E63S from them, the AMG GT C was a private purchase. The service manager spent an hour with me, at a shop that's crammed to capacity with other customers. He's committed to fix the issue, come what may, and I appreciate that. I've had similar positive interactions with other dealerships in the same (Hendrick) group and no negative interactions with multiple cars over the past 11 years.
The P152300 stored code was diagnosed as a "check valve of evap system at partial load is jammed". The cure was to replace both purge lines. To be fair, they can't be 100% sure that this was the fix and will take the car back in again if the issue reoccurs.
Mercedes of Durham is now neck-and-neck with Porsche Southpoint next door to them for best service I've received. They're owned by the same guy and it shows in their service culture.




It's all good news... the EVAP problem is getting better and the excellent dealer seems committed to top grade service.
The underlaying emission system normally has an extended warranty coverage up to 10Yrs I believe. It works to recycle unburned green house fumes from gasoline.


