In theory, and assuming the dreaded 14cux ECU, you could change the tune select resistor and disconnect the lamda sensors.
If the ECU thinks it doesn't have 'em it wont look for 'em. You can use a metal oxide 1 watt or ordinary 1/2watt resistor, for non-cat 3.9's the resistor has a value of 470 ohms.
Yours is likely to be between 3700 ohms and 4100 ohms, can be checked across pins 27 and 5 on the ecu multi plug. Or locate the resistor, should be taped to the ouside of the injection loom close to the ecu.