Fault Conditions (DTC EFI-55x, EFI-545

If the ECM registers misfiring to such a degree that the three-way catalytic converter (TWC) could be damaged (this degree varies with engine speed and load), for 200 engine revolutions (500 ignition sequences), the ECM checks whether the misfiring is coming from a specific cylinder or from different cylinders.

If only one cylinder exceeds the limit, DTC EFI-x is stored first with one of DTCs EFI-451, EFI-452, EFI-453, EFI-454 or EFI-456 and EFI-543, first DTC EFI-545 and then one of DTCs EFI-551, EFI-552, EFI-553, EFI-554 or EFI-555 depending on the cylinder. If more than one cylinder exceeds the limit, DTC EFI-545 is stored with a DTC for the relevant cylinder.