100% Free

No Scanner Needed

Carly logo

Carly Community

rudolfdunkel67

S Klasse Fault Memory Lock Active Message

I'm wrestling with something weird on my 2018 Mercedes S Klasse hybrid. I keep getting a "Fault memory lock active" message. The diagnostics show an error stored in the error memory, but it's vague. From what I've gathered, it seems like a possible undervoltage situation in the car's electrical system is triggering this. Has anyone else run into this particular gremlin? I'm trying to avoid just throwing parts at it, automotive diagnostics is a pain. I am quite good with car electronics, but this active memory thing is new to me.

4 comment(s)

benjaminsmith9

I had a similar issue with my S Klasse. The fault codes kept popping up, pointing to some random electrical glitches. I would check your battery first. Modern car systems are very sensitive to voltage drops. Also, have you recently had any work done on the car's electrical system? Sometimes, a loose connection or a module not properly initialized can cause these types of errors.

rudolfdunkel67 (Author)

Interesting. No recent work done, but the battery is a good point. The car does sit for extended periods sometimes. When you say similar, was it also the "Fault memory lock active" message specifically? And did you end up resolving it yourself, or did it require auto repair?

benjaminsmith9

Yes, it was the exact same "Fault memory lock active" message. I initially tried troubleshooting myself, checking fuses and connections, but ultimately, I took it to a workshop specializing in car electronics. They confirmed it was indeed related to undervoltage, possibly exacerbated by the hybrid system's complexity. They performed some resets and re-initializations, and the problem hasn't returned since.

rudolfdunkel67 (Author)

Appreciate the confirmation and advice. Seems like a trip to a specialist is the way to go. Booked it in for automotive diagnostics. Turns out you were spot on with the undervoltage issue. The workshop found a minor parasitic drain and some older software issues. They sorted it all out for 240€ Thanks again for pointing me in the right direction!

Join the discussion now: