Mercedes-Benz E-Class Saloon Owner's Manual page 540

538 Display messages and warning/indicator lamps
Display messages Possible causes/consequences and
Uncouple the trailer and secure it against rolling away.
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Initiate a new swivelling procedure and do not re-couple the trailer until the display message disappears.
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If the display message does not disappear, the trailer tow hitch is defective and the ball neck is not locked.
Do not couple up the trailer. Drive on without the trailer. Note the reduced ground clearance due to the
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unlocked ball neck.
Consult a qualified specialist workshop.
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The trailer tow hitch is not operational when the vehicle is at a standstill.
Uncouple the coupled trailer and secure it against rolling away.
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Initiate a new swivelling procedure (
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If the ball neck is retracted: press and hold the button on the boot lid until the ball neck engages vertically in
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the locked position and then engages beneath the bumper.
If the ball neck is extended: press and hold the button on the boot lid until the ball neck engages beneath the
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bumper.
If the display message does not disappear, the trailer tow hitch is defective and the ball coupling is not locked.
Do not couple up the trailer. Drive on without the trailer. Note the reduced ground clearance due to the
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unlocked ball neck.
Consult a qualified specialist workshop.
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M M Solutions
page 264).
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