I Just bought the ML230 with 55000 miles. The used car dealer told me I needed to replace the gas gauge sending unit because it showed empty even though it was full. I drove it a few days then filled it till the gas pump just clicked off. The gas gauge went to full then slowly dropped to empty while driving about 30 miles. The next day it was on full and worked fine till the gauge was near empty. I filled it again till the pump clicked off and the gauge showed full but over the next 15 miles it dropped to 1/2 full. Tomorrow I will check to see it goes back to full. Has anybody else had this problem?

 

I had the same problem with myML 500. I had to return it to the dealership 3 times because they were not fixing the correct thing. They replaced the fuel sending unit, hoses and other parts. Nothing. They replace the guage in the console and it has been working fine since then. I nor MB really knew what the problem was with the car but it is working now.....