Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
Hello and Welcome! I'm Billy and i will assist you with your inquiry. Feel free to ask if any further info is needed.If you get prompted for a Premium service or a phone call, please ignore that, as i don't think it is needed at this point.
My apologies for the delay, thank you for your patience.
Thank you for all the details as those are key. From you detailed description, i can tell you this:
The engine module is not going in limp mode (and i think that the EML is off). The transmission however is going in to limp mode preventing the manual mode and causing the delayed shifts.
In which case the transmission module and the shifter module will need to be checked using the scan tool (diagnostic equipment) and the fault codes in those modules retrieved. I would also advise that the transmission fluid be checked and topped up for now if needed.
I would not recommend replacing the fluid yet, as the most common fault on this model's transmission would be the conductor plate inside the transmission. If we confirm that this is faulty the transmission sump will require removal to access this part, so the fluid will require replacement then.
Kindly let me know if further assistance is required on this matter and get back to me with the fault codes if needed, I will be able to explain those and provide guidance on the diagnostics procedure in order to confirm the faulty part. That way we avoid replacing unneeded parts.
Indeed, a diagnostic report that would retrieve the faults mainly from the transmission. Even if the problem is not present at the exact moment, the codes will be stored under thee "history codes" tab.