Nissan 350z 2004 - Fault Codes P0300, P1615, P0132, P0152, and P0128 After Cat Converter and ECU Replacement
I recently replaced the catalytic converter with an aftermarket unit and upgraded to a new ECU. The vehicle starts smoothly but exhibits hesitation during driving. I have already replaced the spark coils and fuel pump. Could an internal vacuum leak be causing this issue? Any insights or troubleshooting steps would be greatly appreciated. Andrew
Use your OBD2 scanner to check the ECT (Engine Coolant Temperature) sensor readings, as well as the B1S1 and B2S1 oxygen sensor voltages. High voltage readings may indicate a rich fuel mixture or wiring problems. The P1615 code points to a security system issue—this could be resolved by reprogramming the new ECU with factory settings. For reliability, it's recommended to stick with original Nissan parts and avoid aftermarket components unless properly verified.