P0550 NISSAN Power Steering Pressure Sensor Circuit Malfunction

Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Power steering inoperative
Possible causes
- Power steering pressure sensor harness or connectors
- Power steering pressure sensor harness is open or shorted
- Power steering pressure sensor
When is the code detected?
An excessively low or high voltage from the sensor is sent to ECM.
P0550 NISSAN Description
Power steering pressure (PSP) sensor is installed to the power steering high-pressure tube and detects a power steering load. This sensor is a potentiometer which transforms the power steering load into output voltage, and emits the voltage signal to the ECM. The ECM controls the electric throttle control actuator and adjusts the throttle valve opening angle to increase the engine speed and adjusts the idle speed for the increased load.

P0154 NISSAN O2 Sensor Circuit No Activity Detected Sensor 1 Bank 2

Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- High Fuel Consumption
- Excessive Smoke from Exhaust
Possible causes
- Front Heated Oxygen Sensor Bank 2 harness is open or shorted
- Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection
- Faulty Front Heated Oxygen Sensor Bank 2
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks
Tech notes
Replacing the O2 Sensor 1 usually takes care of the problem
When is the code detected?
The voltage from the sensor is constantly approx. 0.3V.
P0154 NISSAN Description
The front heated oxygen sensor (or O2 sensor 1) is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The heated oxygen sensor 1 has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. The heated oxygen sensor 1 signal is sent to the Engine Control Module (ECM). The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1V to 0V.