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2015 Mercedes-Benz S550 4MATIC, 2021 GLC300 4MATIC Coupe and 2006 S500 RWD
3 error messages came out of nowhere (Pre-Safe)
I get 2 messages when I initially start the car last night. The “Pre-Safe Function Limited” and “Active Lane Keeping Assist Inoperative”. It wasn’t that cold and the car is clean from what I see. I clean my car every week. Then when I engage my Distronic Plus the cruise control part works but the error message “DTR+: Steering Assist Inoperative” comes up. I checked my front seat belts they are ok and the tensioner part works. I fear one of the radars are broken but I don’t know the locations.
My car pops "Active Lane Keeping Assist Inoperative" sometimes after a cold front blows in. Strange. Generally, these spurious message correlate to a weak aux battery, which is cheap enough to just change as a diagnostic measure.
2015 Mercedes-Benz S550 4MATIC, 2021 GLC300 4MATIC Coupe and 2006 S500 RWD
Originally Posted by Tom in Austin
My car pops "Active Lane Keeping Assist Inoperative" sometimes after a cold front blows in. Strange. Generally, these spurious message correlate to a weak aux battery, which is cheap enough to just change as a diagnostic measure.
Get a small paint brush (say ½ inch) and next time you wash your car--find those little holes in the surface where radar and ultrasonic signals leave the car and return to be measured.
Then after washing the car, dip the brush in the opening ring of the hole and gently wash the accessible parts of the transceiver.
I get these messages when ice covers those holes, or when dirt crusts over the holes.
Its like trying to use a radar gun from behind bushes.
I get 2 messages when I initially start the car last night. The “Pre-Safe Function Limited” and “Active Lane Keeping Assist Inoperative”. It wasn’t that cold and the car is clean from what I see. I clean my car every week. Then when I engage my Distronic Plus the cruise control part works but the error message “DTR+: Steering Assist Inoperative” comes up. I checked my front seat belts they are ok and the tensioner part works. I fear one of the radars are broken but I don’t know the locations.
It can be a voltage transient that impacts CAN-Bus thresholds
It is true that good batteries and clean radar are necessary but when it keeps happening twice a month regardless of your efforts and parts... you go out looking for solid answers.
Get yourself a LAUNCH scanner to read ALL faults. They will be set with "Stored" status become they are on the threshold between good/bad.
My car pops "Active Lane Keeping Assist Inoperative" sometimes after a cold front blows in. Strange. Generally, these spurious message correlate to a weak aux battery, which is cheap enough to just change as a diagnostic measure.
Get a small paint brush (say ½ inch) and next time you wash your car--find those little holes in the surface where radar and ultrasonic signals leave the car and return to be measured.
Then after washing the car, dip the brush in the opening ring of the hole and gently wash the accessible parts of the transceiver.
I get these messages when ice covers those holes, or when dirt crusts over the holes.
Its like trying to use a radar gun from behind bushes.
I'm going to second this. I could be as simple as dirty sensors.
On my Panamera, I would periodically get a message directing me to clean the radar sensors.
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