1. Locate the OBD-II port in the driver’s footwell area of your Nissan. It is typically hidden under a plastic cover.
2. Connect the OBD-II code reader to the OBD-II port. Ensure that the scanner is compatible with the Maxima.
3. Turn the ignition key to the “On” position (without starting the engine) and wait for the OBD-II code reader to turn on and initialize.
4. Once the scanner is ready, it will display any fault codes stored on your Maxima’s engine control unit (ECU). Check the manual or go online to find more about the specific codes.
5. Write down the codes on paper for reference. You can also clear them from the OBD-II reader's memory for troubleshooting.
Step 2: Locate and Inspect Components
1. Locate and inspect the oxygen sensors. They are typically screwed into the exhaust manifold and catalytic converter. Disconnect their electrical connectors and check for any visible signs of damage. If the sensor tips are dirty or coated in soot, they will need to be cleaned or replaced.
2. Check the mass airflow sensor located in front of the throttle body. Inspect its electrical connector and sensor element. Clean the sensor element with a mass airflow sensor spray if it appears dirty. Replace it if there are any signs of damage.
3. Inspect the spark plug wires by lifting the spark plug wire boot one by one and checking the connector. Replace the wires if they are loose, damaged, or brittle.
4. Check the fuel injector connectors and fuel pressure.
Step 3: Fix the Problem
1. Once you have identified the root cause of the illuminated “Service Engine Soon” light, you need to fix it based on what the diagnosis is. Repairs can range from simple replacements (such as an oxygen sensor or spark plugs) to more involved repairs (like a faulty catalytic converter).
2. If you are unable to perform the repair yourself, take your Nissan Maxima to a certified mechanic or automotive repair shop for assistance.
Step 4: Turn the Warning Light Off
1. Once the issue is fixed, turn the ignition key to the “On” position (without starting the engine) again and use the OBD-II scanner to clear any remaining OBD-II codes. This will turn off the “Service Engine Soon” light.
Note: For this method to work, the service engine soon light has to be caused by a problem detected through the vehicle’s onboard diagnostics. If the problem was just a loose gas cap or another similar issue, clearing the code may only cause it to reappear after the onboard system resets.
