The engine management electronic control unit (ECU) is electronically coded for the specific vehicle, and new units are supplied without a code; if replacing the ECU, a Nissan dealer must program the new unit with information from the old one. The ECU is located on the left side of the engine compartment, positioned on the left of the air cleaner assembly for Type 1 engine models and in front of the battery for Type 2 models. Begin by disconnecting the battery negative terminal, then for Type 1 models, remove the air cleaner assembly. Release the locking levers and withdraw the three electrical connectors from the top of the ECU, then undo the four retaining nuts to remove the ECU from the mounting bracket, ensuring secure reconnection of wiring during refitting. The crankshaft position sensor is located at the rear of the transmission bellhousing; disconnect the wiring connector, undo the retaining bolt, and withdraw the sensor from the cylinder block/bellhousing, applying a new O-ring seal and engine oil to aid installation during refitting. The camshaft position sensor is fitted to the transmission end of the cylinder head cover; access it by removing the plastic engine shield, disconnect the wiring connector, undo the retaining bolt, and withdraw the sensor, discarding the old O-ring seal and using a new one during refitting. The mass airflow sensor, which includes the inlet air temperature sensor, is mounted in the air cleaner housing; remove the air cleaner assembly, undo the retaining screws, and remove the airflow sensor, recovering and renewing its sealing ring. Refitting involves using a new sealing ring and securely tightening the retaining screws. The inlet air temperature sensor is combined with the mass airflow sensor, requiring removal of the mass airflow sensor. For the throttle valve housing, remove the inlet air duct and intercooler outlet pipe, disconnect the wiring connector, unscrew the bolts from the mounting bracket and the EGR valve housing, and remove the unit, discarding the gasket/seal, with refitting requiring a new gasket/seal.
Posted by NissanPartsDeal Specialist 
