P1288 INFINITI Code – Air Fuel Ratio Sensor 1 Slow Response Circuit Bank 2

 

 

📌 Meaning of INFINITI Code P1288

Code P1288 is triggered when the ECM (Engine Control Module) detects that the response from the Air/Fuel (A/F) Ratio Sensor #1, Bank 2 is too slow to switch from a rich mixture to a lean mixture.

This “wideband” type sensor accurately measures the air/fuel ratio, not only at λ = 1 (stoichiometric mixture), but also in rich and lean ranges. It uses an oxygen pumping system to regulate gases in a diffusion chamber and provide a precise signal to the PCM.

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⚠️ Possible Symptoms

• 🔥 Check Engine Light On

• ⛽ Rough Idle or unstable idle

• 🌬️ Abnormal Fuel Consumption

• 🐢 Slight Loss of Performance

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📍 Possible Causes of INFINITI Code P1288

• ❌ Faulty A/F Sensor (Bank 2, Sensor 1)

• 🔌 Damaged Sensor Wiring Harness or Connector

• ⚡ Faulty Electrical Connection (bent pin, corrosion, etc.)

• 🛠️ Fuel Pressure Too Low

• 💨 Intake Air Leak or Exhaust Leak

• 💉 Faulty Fuel Injector

• ⚙️ Faulty Mass Air Flow (MAF) Sensor

• 🔁 Faulty PCV (Positive Crankcase Ventilation) Valve

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🔍 When is Code P1288 Detected?

The ECM expects a fast response from the A/F sensor after startup or acceleration. If the signal takes too long to indicate a switch from rich to lean, it triggers DTC P1288.

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🧰 How to Fix Code P1288?

1. Visual Inspection:

   • Check the condition of the A/F sensor wiring (Bank 2, Sensor 1)

   • Look for bent, corroded, or broken pins

2. Test the A/F Sensor:

   • Use an OBD2 diagnostic tool to read the sensor’s real-time values

   • Check if it reacts to accelerations/decelerations

3. Check for Leaks:

   • Air leak in the intake hoses

   • Exhaust leak before the sensor

4. Check Fuel Pressure

   • Pressure that is too low can distort the air/fuel ratio

5. Test the Fuel Injector and PCV Valve

   • Ensure they are functioning correctly

6. Replace the A/F Sensor if all checks are good but the code persists

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💡 Pro Tip

The A/F sensor operates at very high temperatures (700-800°C). If the sensor’s internal heater is faulty, the sensor will take longer to reach its operating temperature, which can also trigger this code. This point is often overlooked during diagnosis.