Nissan Cipher OBDII Monitor: ECU Reset and Relearn Procedures

The Nissan Cipher, known as the Infiniti G35 in North America, utilizes an OBDII (On-Board Diagnostics II) system to monitor engine performance and emissions. Occasionally, after replacing sensors or performing certain repairs, the ECU (Engine Control Unit) may require a reset and relearn procedure to function optimally. This article outlines the steps involved in resetting the ECU and performing various relearn procedures for the Nissan Cipher. Understanding these procedures can help ensure your vehicle runs smoothly and efficiently.

ECU Reset: The Simplified Method

Resetting the ECU can often resolve issues related to sensor replacements or minor system glitches. While various methods exist, this simplified approach provides consistent results without requiring precise timing:

1. Ignition ON: Turn the ignition key to the “ON” position (do not start the engine). Wait for three seconds.
2. Pedal Pumps: Quickly and fully depress and release the accelerator pedal five times.
3. Hold Pedal: After the fifth pump, fully depress the accelerator pedal and hold it down. Wait for 10 seconds.
4. Blinking SES: Continue holding the pedal down. After approximately 12 seconds, the Service Engine Soon (SES) light should begin blinking.
5. Release and Repeat: Release the accelerator pedal. Wait 10 seconds, then depress and hold the pedal again for 10 seconds. Release the pedal.
6. Turn Off and Start: Turn the ignition key to the “OFF” position. Wait a few seconds, then start the engine. The ECU reset is complete.

Relearn Procedures

Following an ECU reset, certain relearn procedures may be necessary. These procedures allow the ECU to adapt to new sensor readings and optimize engine performance:

Accelerator Pedal Release Position Learning

This procedure teaches the ECU the position of the accelerator pedal when fully released:

1. Ensure the accelerator pedal is fully released.
2. Turn the ignition “ON” for at least two seconds.
3. Turn the ignition “OFF” and wait at least 10 seconds.
4. Repeat steps 2 and 3.

Throttle Valve Closed Position Learning

This procedure helps the ECU learn the closed position of the throttle valve:

1. Ensure the accelerator pedal is fully released.
2. Turn the ignition “ON.”
3. Turn the ignition “OFF” and wait at least 10 seconds. You should hear the throttle valve motor operating during this time.

Idle Air Volume Learning (Throttle Position Learning)

This procedure calibrates the idle air control system:

1. Perform the Accelerator Pedal Release Position Learning procedure.
2. Perform the Throttle Valve Closed Position Learning procedure.
3. Start the engine and let it warm up to normal operating temperature.
4. Turn the ignition “OFF” and wait at least 10 seconds.
5. Ensure the accelerator pedal is fully released, turn the ignition “ON,” and wait three seconds.
6. Quickly pump the accelerator pedal fully five times within five seconds.
7. Wait seven seconds, then fully depress the accelerator pedal and hold for approximately 20 seconds until the SES light stops blinking and stays illuminated.
8. Release the accelerator pedal within three seconds after the SES light turns on.
9. Start the engine and let it idle.
10. Wait 20 seconds.
11. Rev the engine a few times to ensure proper idle speed and ignition timing.

Conclusion

Performing ECU resets and relearn procedures on your Nissan Cipher is essential after certain repairs or sensor replacements. These procedures ensure the ECU functions correctly with the new components, optimizing engine performance and fuel efficiency. Following these guidelines will help you maintain your vehicle and avoid potential issues.