You can go get codes at other module and also check the EGR [ there was a change Campaigne on this part for your chassis], but the first thing to do is... next time it wont start , tap the OverVoltage Relay a few light taps and try to start ..
If it starts right up, pull the relay and see if it is original [ Siemens manufacturer ] .. if it is , upgrade to the newer part #
Archives on "OVP"