As noted by Red Leader, the ECU makes dynamic adjustments to the air/fuel mixture. If your car has a low restriction exhaust system fitted, it will likely throw the P0173 code on an unfortunately regular basis. The ultimate fix (assuming no other issues-follow RL's advice on checking for these) is to procure an unlocked ECU which allows you to capture the adjusted operating parameters and store them as a new baseline map, from which the ECU can again make dynamic adjustments.
Just as a reminder, the dynamic adjustments the ECU (standard or unlocked) makes are lost if the battery is disconnected for any reason. Hence the value of the unlocked ECU with which you can record the adjusted map file using the ProTune software.
Last edited by Bitsobrits; 08/06/25 06:23 PM.
