Originally Posted by q2bruiser2

Yesterday I was running errands in the SL and all was well with the world. Beautiful day in Colorado with the top down, high 70s F and I stopped to fill the tank with fuel. After fueling, got in the car and no start. The screen filled with dialogs like a 2000s **** website with the main being (paraphrased): Service Required. Do not change transmission from Park.

After 4-5 attempts to start I gave up and decided to call Mercedes Assistance for a tow ... which would be the second in as many weeks. After about 10 minutes and while on the phone with MA, I hit the starter button again and it cranked with no check engine, no messages or alerts in the Service Menu. I drove the car home without incident.

Any idea guys? I've searched and the best I can come up with is a possible battery issue? My battery was replaced under warranty less than 2 months ago and I drive the car most every day. If not driving for a few days I put it on the trickle charger. I've received no low battery warnings.

Any information would be appreciated.

Originally Posted by tepelena

I've encountered similar no-start issues that could be due to several factors. It might involve the ISM intermittently failing to communicate with the vehicle’s systems, or a faulty starter relay disrupting the ignition process. Additionally, the transmission range sensor could be sending incorrect signals about the gear position, preventing the car from recognizing that it's in Park. Another possibility is an issue with the vehicle’s immobilizer system, where the key fob isn't consistently communicating with the car’s security system, triggering the "Service Required" alerts. To diagnose this properly, you should read fault codes from multiple control units such as the ISM, ECU (Engine Control Unit), and TCU (Transmission Control Unit). I recommend using a full system scanner like youcanic’s full system scanner, which effectively diagnoses all system modules. Be cautious with generic OBD2 scanners like the Autel AutoLink AL319, which only scan engine-related codes and won’t detect issues in other control modules. If you’re not comfortable handling this yourself, taking the vehicle to a mechanic with the right equipment is your best bet.

Originally Posted by q2bruiser2

Finally have an update. The transmission valve body is being replaced. They tried a software update which failed so replacement is required. Hopefully will have it back in a week.

Originally Posted by W205C43PFL

Glad they found the cause, hopefully this replacements fixes the issue so you can be back in the vehicle enjoying it again.

Originally Posted by q2bruiser2

The valve body has been replaced but when they were cleaning it for return their wash person power washed my PPF off over the windshield so am now waiting for them to fix. Lesson learned. Never let the dealer wash your car.