NISSAN Code P1273: Causes, Symptoms, and Repairs

1. What is Code P1273 on a Nissan?

Code P1273 is an OBD-II error code specific to Nissan vehicles. It is related to the Air/Fuel Ratio (A/F) sensor, which plays a crucial role in managing the engine’s air-fuel mixture.

2. Possible Causes of Code P1273

Code P1273 can be triggered by several factors:

✅ Faulty Air/Fuel Ratio Sensor (A/F 1, Bank 1)
✅ Damaged A/F Sensor Wiring Harness (or short circuit)
✅ Poor Electrical Connection of the A/F Sensor
✅ Fuel Pressure Problems
✅ Faulty Fuel Injector
✅ Faulty Mass Air Flow (MAF) Sensor

3. Symptoms of Code P1273

When this code is detected, you may experience the following symptoms:

🚨 Illuminated Engine Light (“Check Engine”)
🚨 Irregular Engine Idle
🚨 Abnormal Fuel Consumption
🚨 Loss of Engine Power

4. When is This Code Detected?

Code P1273 is recorded when the signal from the A/F Sensor 1, Bank 1, is shifted towards a lean mixture for an extended period. This means that the ECM (Engine Control Module) detects an imbalance in the air-fuel ratio.

5. Technical Description of the A/F Sensor

The Air/Fuel Ratio (A/F) sensor is an advanced sensor that precisely measures the air-fuel mixture over a wide range, including both rich and lean mixtures.

🔹 Structure: The A/F sensor contains a Nernst cell and an oxygen pump cell, which work together to balance the exhaust gas concentration.
🔹 Operating Temperature: It is equipped with an integrated heating element that maintains a temperature of 700 to 800 °C (1,292 – 1,472 °F).
🔹 Operation: Through an electronic circuit, it adjusts the pump current to maintain a stable exhaust gas composition at λ = 1.

6. How to Repair Nissan Code P1273?

To diagnose and fix this issue, follow these steps:

✅ Step 1: Check Electrical Connections

• Inspect the A/F sensor wiring harness.
• Look for broken, bent, corroded pins, or poor connections.

✅ Step 2: Test the Air/Fuel Ratio Sensor

• Measure the A/F sensor resistance using a multimeter.
• Check if the integrated heater is functioning correctly.

✅ Step 3: Check Fuel Pressure and Supply

• Test the fuel pressure to ensure it meets the manufacturer’s specifications.
• Inspect the fuel injectors for possible blockages or leaks.

✅ Step 4: Check the Mass Air Flow (MAF) Sensor

• Clean the mass air flow sensor with a specific MAF sensor spray.
• Verify that the MAF sensor is sending correct data to the ECM.

✅ Step 5: Reset the Error Code

• Once repairs are completed, use an OBD-II scanner to clear the P1273 code.
• Perform a driving test to see if the problem persists.

7. Conclusion

Nissan Code P1273 is often related to a faulty or poorly powered Air/Fuel Ratio sensor. However, fuel issues or a faulty air flow sensor can also be the cause. A thorough inspection of the injection system and sensors is essential to resolve the issue.

🔧 If Code P1273 persists after repair, it is recommended to consult a professional for an in-depth diagnosis.