Nissan Repair: amber check engine light on, autozone, speedometer

Question
I RECENTLY HAD THE CHECK ENGINE SERVICE PERFORMED, BUT THE LIGHT STILL COME ON FROM TIME TO TIME I NOTICE THAT WHEN IT DOES COME ON THE SPEEDOMETER DROPS TO 0 MILES PER HOUR. WHAT SHOULD BE DONE TO CORRECT THIS? THIS IS A 95 PATHFINDER, SIX CYLINDER

Answer
You need to get a code reader to answer the question properly.  I bought a reader due to the cost of getting a shop or dealer to check the codes.  Now, Autozone and other parts stores check the codes for free.  Have the code checked and I can properly answer the question.