P1289 - FAULT CODE - OBD2

P1289 INFINITI, NISSAN: AIR FUEL RATIO SENSOR 1 CIRCUIT SLOW RESPONSE BANK 2

The A/F Sensors are installed in the exhaust system to measure the amount of oxygen present in the exhaust accurately. The readings collected by these sensors are sent to the ECM (Engine Control Module). Then, it will adjust the air/fuel mixture parameters as necessary to make the mixture as stoichiometric as possible.

Inside the Air/Fuel Ratio Sensor is a heater. When it is activated, the time it takes for the sensor to reach a temperature necessary to detect oxygen faster decreases. However, if you compare the conventional oxygen sensors to the A/F sensors, the A/F sensors provide a wider range of accurate readings. These electrical signals are clear and continuous over the range of (0.7 < λ < air).

The P1289 OBDII fault code P1289 is a code used by Infiniti and Nissan brand manufacturers to indicate that the rich-to-lean response of the A/F signal calculated by the ECM via the Air/Fuel Ratio Sensor 1 has taken longer than the allowed time.

• Check Engine light ON.
• The motor is running erratically.
• Unstable idling performance.

Reasons to set the DTC P1289 OBD2 DTC code:

• There may be damage to the wires or connectors of the Air/Fuel Ratio Sensor 1 on bank 2.
• The A/F sensor number 1 may be faulty.
• Fuel pressure may not be enough.
• A fuel injector may be in poor condition.
• The engine may have intake or exhaust air leaks.
• The airflow meter is possibly in bad condition.

To troubleshoot the P1289 OBDII diagnostic code, consider this:

• Consult the TSBs.
• Use an automotive scanner and check if other error codes are stored. If so, diagnose the codes following the order shown by the scanner.
• Check the Air/Fuel Ratio Sensor 1 circuit for bank 2 for wires or connectors with certain deficiencies caused by wear, corrosion, or burns. Repair or replace if such conditions are discovered.
• Check if the fuel pressure is enough. In case this value is not the one indicated by the manufacturer on the vehicle's information source, check the integrity of the fuel injectors. Also, make sure the engine is not leaking air. Repair as necessary.
• Use the appropriate tools and measure the resistance of the A/F Sensor. This value should match the value specified by the manufacturer in their specifications. If not, replace the sensor.