i recently had a JDM type r put into my 94 gs-r. eveything seems to be okay except that the ECU keeps throwing a code 6. i've changed the sensor and it still does it. can anyone tell me how to check the circuit to the sensor? if that means checking the voltage, i've already done that and it checks out fine. what else could be causing this? could air in the coolant lines do it? please help!!!!