john w. delodder

One thing I should have said. The oxygen sensor is often times called the exhaust sensor because it sends information about the O2, HC, N2, CO2 etc. to the electronic control unit which sends information to the fuel injection system to adjust the air/fuel mixture. It is located on the exhaust pipe near the exhaust manifold on 1990, 1991 and 1992 Maximas. Don't know anything about earlier or later models. There are two systems that operate. One is when the engine is cold called the open loop. It acts like a choke. When the engine is warm another system takes over and it is called the closed loop. When the connector was shorting out(?) the system was put into the open loop and raw fuel was sent to the cylinders or the air/fuel mixture was on cold mode when the engine was in fact warm. The engine loaded up with excess fuel and ran rough. Makes sense to me. I called the Nissan dealer and talked with a mechnic and he told me the suggested Nissan maintenance is to replace the exhaust sensor every 30K and had I done that I probably would have found the problem before it happened. I need to pay closed attention to the book. JWD