Hi, I can only assume you have some sort of Duramax equipped vehicle. I could be more helpful if I knew what it was.
DTC P0207: #7 Injector Driver Fault. (This is the farthest one back on the passenger side of the engine.)
DTC P2146: Injector Positive Voltage Relay Control Circuit Group 1 (Injectors 1, 4, 6, and 7)
If these are the only 2 DTC's you have, the most likely problem is that the injector connector on cylinder 7 is not fully supported near the connector and it is susceptible to terminal breakage from engine vibration. This applies to the LLY engine (VIN code 2). There are new 90* connectors along with harness support brackets available to correct this issue. Check the #2 injector connector also. (Driver's side, furthest forward.)
Another possibility is a chafed wire harness at the aluminum FICM (Fuel Injector Control Module)bracket.
The Duramax has a pretty good base warranty and you may be able to get the repairs covered at a Chevy or GMC dealer.
Jim & Linda
'03 Winnebago Adventurer 35U (W22)
'06 Saturn Vue Toad