A diagnostic code is helpful when troubleshooting a particular problem that has occurred. After the trouble code is defined the problem can be repaired and rechecked. Early Nissan check engine lights are not used to blink out a trouble code like on most vehicles but instead use a mode and retrieval method. Most computers are located behind the glove box, under the passengers seat or in the center console depending on year and model and is set up to work in five different modes, the first three modes of operation are used for the manufacturing and assembly process, mode four is used for trouble code output sequence and mode five is used to read oxygen sensor outputs. Step by step guide on how to retrieve troubles codes from Nissan vehicles 1995 and earlier, including code chart.Step 1 - To boot the computer in mode four make sure the key is in the "OFF" position. Next locate the mode switch on the computer which is either a small toggle or a screw style switch. The screw style switch is activated by turning the screw one way then back the other way.
Step 2 - Turn the key to the "ON" position without starting the engine, next flip the switch or turn the screw. The led light will blink one time for mode one, then two times for mode two, three times for mode three.
Step 3 - When the lights blink four times this is the mode needed to display the trouble codes, flip the switch or turn the screw back. The led light will now blink out the trouble code or codes, the computer must be in mode four to retrieve the trouble codes.
Step 4 - The first led light will blink the first digit of the code number, there will be a pause then the remaining led light will blink out the second digit of the trouble code. For example, if the first led light blinks one time, and the second led light blinked two times the code number would be 12. Some Nissan models are equipped with just one led light in this case the light will blink the first part of the code pause, then continue with the second number of the code. Once repairs have been made the computer codes can be cleared by disconnecting the negative battery terminal for three minutes and then reconnect it.
Code 11 Crank angle sensor
Code 12 Mass airflow sensor
Code 13 Engine coolant temperature sensor
Code 14 Vehicle speed sensor
Code 21 No ignition reference
Code 22 Fuel pump
Code 31 Engine control unit
Code 32 EGR sensor
Code 33 Oxygen sensor
Code 34 Knock sensor
Code 35 EGR temperature sensor
Code 43 Throttle position sensor
Code 45 Injector leak
Code 51 Injector circuit
Code 54 Automatic transmission signal
Code 55 No malfunction recorded
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