P1272 - FAULT CODE - OBD2

P1272 INFINITI, NISSAN: AIR FUEL RATIO SENSOR 1 BANK 1 CIRCUIT NO ACTIVITY DETECTED

The Air/Fuel Ratio Sensor measures how much oxygen there is in the exhaust system. If this sensor is compared to conventional O2 Sensors, which vary their signal according to the fuel mixture, the A/F Sensors give wider and more accurate readings of the oxygen present in the exhaust. Then, it sends an electrical signal that accurately applies to that value.

The Powertrain Control Module (PCM) provides the A/F Sensors with a 2.6 reference voltage. Although on certain systems 3.3 volts are sent. It also works as a power supply. As changes in the fuel mixture occur, the signal voltage flows in a negative direction when the mixture is rich, and if the mixture is lean, it flows in a positive direction.

During proper operation of the Air Fuel Ratio Sensor and the exhaust system, the current flow stops as long as the mixture is optimal. In other words, the fuel burned uses the available air. However, in case the mixture conditions are out of the proper parameters due to performance problems of the A/F 1 Sensor for bank 1, the fault code P1272 OBDII will be set.

• The Check Engine turns on.
• Irregular motor operation.
• The engine is unstable at idle speed.

The diagnostic code P1272 OBD2 is stored for these reasons:

• A/F Sensor 1 connectors or cables may be faulty.
• The Air/Fuel Ratio Sensor may be defective.
• Maybe a fuel injector is damaged.
• The fuel pressure may not be within the required levels.
• The airflow meter may be faulty.

To troubleshoot the DTC P1272 OBDII code, consider this:

• Locate the vehicle's information source to access the Technical Service Bulletins (TSB). The information included in these is very useful.
• Verify that there is no damage to the electrical components of the A/F Sensor circuit. Fix conditions such as corrosion, burns, or other damage.
• Check that the fuel injectors are in good condition. If you detect irregular operation in one of these, the fuel pressure will also be deficient. Make the respective adjustments.
• Measure the resistance of the Air Fuel Ratio Sensor 1 and the proper continuity of its circuit. These values should match those specified by the manufacturer. If not, make the appropriate corrections.