Ray
 

I have a C200 Elegance 1998 model. The petrol gauge is unreliable. The garage has replaced the senders with no changes to the symptoms. When the car is on short journeys the gauge does not return to zero when the ignition is off. The next time it is turned on the gauge lurches further up . Eventually it is right off scale. After long journeys the gauge is still unreliable but when the ignition is turned off the needle returns to zero and when restarted the gauge reads correctly. Has anyone any explanation?