u/Taratorr

I have a 2014 CLA 45 running a stage 1 tune, whenever it gets really hot outside the car just shuts down and we get a “fuel pump low voltage” code, we have changed the fuel pump and the fuel pump control module, but still whenever it gets hot outside it just stalls and runs for about 20 seconds.

We have tested it when the temperatures are cooler and it runs for 2+ hours without issue. The shop says that the only other thing that could be the culprit is the ECU tune.

Is it possible something is messed up in the remap file that makes the car shut down whenever the ambient temperature is high?

2014 Mercedes CLA 45 M133 engine at about 90,000 km

A month or so ago was driving at about 30 km/h and the car randomly stalled, waited a minute, turned it back on and after 1 minute stalled again, started it back up and managed to get back home (was 20 seconds from home).
After 30 minutes or so of the car turned off I took it to a mechanic to scan for codes and “Fuel Pump Low Voltage” was the only code that appeared, and he told me to drive it until it happens again.

Fast forward 10 days later and the same thing happens- low speed in traffic, car suddenly dies again, stopped and waited for 30 seconds and started it back up, but i waited instead of driving off and not 10 seconds later it starts ruining rough (i presume on 3 cylinders).
While running, it starts to stall and suddenly starts up again runs for another 30 seconds and the completely stalls.

At that point i decided to call a tow truck and took it to the mechanic again and this time we had:
P0506 – Idle Air Control System: RPM Lower Than Expected
P261029 – The engine off time has an implausible value / There is an invalid signal

So we decided to change the fuel pump considering the first fault that appeared, but not even 20 minutes after taking it from the shop it did it again and at this point we don’t know what to do, because he has scanned it while the car is running rough and nothing shows up except P0506

We have changed the thermal paste of the fuel pump module as it does get hot, but I’m not really sure that’s the culprit as i don’t understand why this only happens at low speeds when there isn’t such load on the fuel pump

The only thing i have concluded is that this only happens when its above 30°C and at low speeds or at traffic lights

Any suggestions what to look for, because replacing random parts and hoping it fixes something isn’t the most financially sensible thing to do.

VIDEO OF ISSUE IN COMMENTS

This has been happening for quite a while now, for instance if there is police reported ahead in about 2 or so kilometres, the moment i come close to it the report disappears, after i have passed where the report should have been if i move the map back to the report there are in some cases 5 or more reports of the speed trap, this only happens in CarPlay, we have tested it with a phone simultaneously running Waze while not connected to the car, and it shows all the reports and gives the notification, my phone is updated, Waze is updated, Ive tried on 3 different cars with CarPlay and the same thing happens