Originally Posted by ExpensiveTaste

My wife's car is having the same problem (P1093 keeps coming back with P0313 when fuel is low) after replacing the throttle body elbow when P0174 was the code. We've tried replacing all O2 sensors, spark plugs, thermostat, air filter, fuel filter/regulator, and had a smoke test done coming up with no leaks. We've tried swapping the injectors on bank 1 and bank 2 to no avail.

FYI, the P1093 comes up as Fuel Trim too Rich in second bank (Cylinders3-6). Others have further explained the cause of the error as a lean condition causing fuel trims to reach their limit of dumping fuel in (1). P1093 is said to be equivalent to BMW code 236 which is Pre-Cat Bank 2, Fuel Trim.

I'm curious as to what the difference is between P1093 and P0174 (system too lean bank 2).

The next thing we're going to try is swapping the coils on bank 1 to bank 2.