P1273 NISSAN – Air/Fuel Ratio Sensor 1, Bank 1 Lean Shift Monitoring

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.

P1129 AUDI – Long Term Fuel Trim System B2 Too Rich

P1129 AUDI Possible Causes

  • Faulty mass air flow (MAF) sensor
  • High fuel pressure
  • Purge canister solenoid stuck open
  • Faulty Bank 1 HO2S

How to Fix P1129 AUDI Code?

Start by checking the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Check engine light on (or service engine soon warning light)

P1129 AUDI Meaning

Long term fuel trim system B2 too rich is the generic description for Audi P1129 code, but the manufacturer may have a different description for your vehicle model and year. Currently, we don’t have more information about the Audi P1129 OBDII code.

P1129 CHRYSLER – Closed Loop Not Achieved Bank 2

P1129 CHRYSLER Possible Causes

  • Fuel system
  • Engine Coolant Temperature (ECT) sensor or wiring connectors
  • MAP sensor or wiring connectors
  • O2 sensor wiring or connectors
  • Engine mechanical system

How to Fix P1129 CHRYSLER Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Check Engine Light on (or Service Engine Soon warning light)

P1129 CHRYSLER Meaning

The Powertrain Control Module (PCM) detects a condition where the vehicle has remained in open loop fuel control, from a start-up condition, longer than a calibrated duration, when conditions would otherwise have closed loop operation.

P1129 DODGE – Closed Loop Fueling Not Achieved Bank 2

P1129 DODGE Possible Causes

  • Fuel delivery system
  • Engine Coolant Temperature (ECT) sensor or wiring connectors
  • MAP sensor or wiring connectors
  • O2 sensor wiring or connectors
  • Engine mechanical system

How to Fix P1129 DODGE Code?

Start by checking the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Check engine light on (or service engine soon warning light)

P1129 DODGE Meaning

The Powertrain Control Module (PCM) detects a condition where the vehicle has remained in open loop fuel control, from a start-up condition, longer than a calibrated duration when conditions would otherwise have closed loop operation.

P1129 FORD – Downstream Oxygen Sensors Swapped From One Bank to Another

P1129 FORD Possible Causes

Crossed HO2S harness connectors (downstream) HO2S wiring crossed at harness connectors (downstream) HO2S wiring crossed at 104-pin harness connectors (downstream)

How to Fix P1129 FORD Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Check Engine Light on (or soon-to-be-service engine warning light)

P1129 FORD Meaning

The Heated Oxygen Sensor (HO2S) monitor determines whether the HO2S signal response for a fuel change matches the correct engine bank. The test fails when a response from the tested HO2S is not indicated.

P1129 HONDA – Manifold Absolute Pressure Sensor Circuit Higher Than Expected

P1129 HONDA Possible Causes

  • Faulty Manifold Absolute Pressure Sensor
  • Manifold Absolute Pressure Sensor harness is open or shorted
  • Poor electrical connection in the Manifold Absolute Pressure Sensor circuit

How to Fix P1129 HONDA Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Check Engine Light On (or Service Engine Soon Warning Light)
  • Engine hard to start
  • Rough or erratic idle

P1129 HONDA Meaning

The Manifold Absolute Pressure (MAP) sensor generates a signal proportional to the amount of vacuum in the intake manifold. The signal is sent to the Engine Control Module (ECM) and the information is used to control the air/fuel mixture ratio. A faulty MAP sensor can cause engine stalling, over-revving, or rough idle.

P1129 JEEP – Closed Loop Not Achieved Bank 2

P1129 JEEP Possible Causes

  • Fuel delivery system
  • Engine Coolant Temperature (ECT) sensor or wiring connectors
  • MAP sensor or wiring connectors
  • O2 sensor wiring or connectors
  • Engine mechanical system

Symptoms

possible

  • Check engine light on (or service engine soon warning light)

P1129 JEEP Meaning

The Powertrain Control Module (PCM) detects a condition where the vehicle has remained in open loop fuel control, from a start-up condition, longer than a calibrated duration, when conditions would otherwise have closed loop operation.

P1129 LAND-ROVER – Left Side to Right Side HO2S Sensors Swapped

P1129 LAND-ROVER Possible Causes

  • Left side to right side swapped HO2S sensors
 

How to fix P1129 LAND-ROVER code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

 
 

Possible Symptoms

  • Check engine light on (or service engine soon warning light)
 

P1129 LAND-ROVER Meaning

Left side to right side swapped HO2S sensors is the generic description for Land-rover code P1129, but the manufacturer may have a different description for your vehicle model and year. Currently, we don’t have any other information about Land-rover OBDII code P1129.

P1129 LEXUS – Malfunction of the Electronic Throttle Control System

P1129 LEXUS Possible Causes

  • Faulty Electronic Throttle Control System (ETCS) actuator
  • Electronic Throttle Control System (ETCS) actuator harness is open or shorted
  • Electronic Throttle Control System (ETCS) actuator circuit Poor electrical connection

How to Fix Code P1129 LEXUS?

Start by checking the “Possible Causes” listed above. Visually inspect the corresponding wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

When is the Code Detected?

The P1129 code is set when the throttle opening angle continues to vary significantly from the target throttle opening angle.

Possible Symptoms

  • Check Engine Light On (or Service Engine Soon Warning Light)

P1129 LEXUS Meaning

The Electronic Throttle Control System (ETCS) consists of the throttle motor to actuate the throttle valve, the electromagnetic clutch to connect the throttle motor to the throttle valve, the throttle position sensor to detect the throttle valve opening angle, the accelerator pedal position sensor to detect the accelerator pedal position, the Engine Control Module (ECM) to control the ETCS, and the single throttle valve body.
The ECM controls the throttle motor to make the throttle valve opening angle properly under responsive driving conditions.
The throttle position sensor which is mounted on the throttle body detects the throttle valve opening angle and provides feedback to the ECM to control the throttle motor.
In case of ETCS malfunction, the ECM cuts power to the throttle motor and the magnetic clutch, and the throttle valve is completely closed by the return spring.
However, the throttle valve opening angle can be controlled by the accelerator pedal via the throttle cable.

P1129 LINCOLN – Downstream Oxygen Sensors Swapped from One Bank to Another

P1129 LINCOLN Possible Causes

Crossed HO2S harness connectors (downstream) HO2S wiring crossed at harness connectors (downstream) HO2S wiring crossed at 104-pin harness connectors (downstream)

How to Fix Lincoln P1129 Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Check Engine Light on (or service engine soon warning light)

P1129 LINCOLN Meaning

The Heated Oxygen Sensor (HO2S) monitor determines whether the HO2S signal response for a fuel change matches the correct engine bank. The test fails when a response from the tested HO2S is not indicated.