How to Reset a Nissan Maxima's Service Soon Light

The Nissan Maxima (known as the Datsun 810 until about 1983) has been around since 1976. Because of this, the Maxima has experienced two different phases of on-board diagnostics. The first phase was experimental and many repair facilities were limited to servicing certain makes and models, sending customers away to the dealerships. The second phase, called OBD II, began in 1996 and standardized the diagnostic equipment used to read trouble codes and reset engine lights. Be aware that the Maxima's engine light should be properly diagnosed (and necessary repairs made, if applicable) before resetting it to prevent other components from being compromised.
Difficulty: Moderately Easy
Instructions
Things You'll Need
OBD II pocket scanner (1996 and newer)
Metric wrench set (1995 and older)
OBD II (1996 and Newer)
1

Open the driver's side door wide enough to get down near the floorboard.
2

Locate the data link connector under the driver's side dash to the left of the steering column.
3

Connect the plug (female) of the pocket scanner to the connector (only connects properly in one position).
4

Turn the ignition key to "On" without starting the engine.
5

Press the erase button on the scanner if it's equipped with one located on the front. If not use the scroll button(s) to toggle through the digital screen display to "clear" or "erase" codes or the "DTCs" option, then follow the directions on the display screen to clear the code. Once the code(s) are clear, provided nothing major is wrong with the Maxima, the service engine soon light will no longer be illuminated.
6

Start the engine of the Maxima and check the instrument panel to verify that the engine light is out. If not, retry the procedure. If it remains on, a "hard" code is present and the vehicle should be serviced as soon as possible.
OBD (1995 and Older)
1

Open the hood of the Maxima.
2

Loosen the black wired negative battery terminal clamp bolt with a metric wrench. Loosen the bolt enough to allow the clamp to be removed from the negative battery post.
3

Turn the headlight switch to the "On" position, then wait 10 minutes.
4

Reconnect the negative battery terminal clamp and tighten the bolt properly so the clamp cannot move.
5

Start the engine to check for the service engine soon light on the instrument cluster. The light should be out because the computer was just reset.

Tips & Warnings

Neither of the procedures illustrated above will "fix" the Maxima. Service engine lights are part of a computerized warning system used to inform the driver that something is wrong. It might be minor, it might serious. But ignoring it and resetting the light can actually do more harm than good. Emissions testing mandated by many states now will detect if a computer code has been reset because the internal monitors will not be in readiness mode and the car will still fail. If the problem has not been fixed, once the monitors are in ready mode, the service engine light will most likely relight on the instrument cluster.

Some mechanics may inform you that removing the negative battery terminal clamp will work on OBD II Maximas as well. While they'd be correct, if the car is equipped with an internal alarm system or a theft-deterrent radio system, these electronic systems will be reset as well and the codes to reset them will have to be obtained from the dealership before operating the car (internal alarm) or using the radio (theft deterrent radio).