Nissan Repair: Nissan Pathfinder 2002 SES light on..., fuel pressure gauge, actron scanner

Question
I have a 2002 nissan pathfinder and got the SES ligth on. The dealer replaced some vaccum sensor and light went away for a day and came back, then replaced the ECM and light came back after 2 days. I got an Actron scanner to read the code and got P1130 saying "Oxygen Sensor Fuel Trim at Limit *codes* A U" what is the solution ... I am tired of this problem.....help......

Alex.


Answer
Alex,

You probably have a fuel condition that is causing the problem.  My guess would be a stuck injector that has caused an over rich condition.  The oxygen sensor is picking this up since the Pathfinder cannot lean out the condition.  Get an adapter and a fuel pressure gauge and check the fuel pr3essure with the key on, then with the engine running and then with the key off.  I bet the pressure is close to normal in the first two modes.  But, when the key is off you should really see a rapid drop in pressure.  This is caused by one or more injectors that are staying off their seats.  The quick and cheap way to check this problem is to pull the plugs and check which one is really black.  Normal spark plugs look light tan to brown.  Over rich ones will be coated black.  The one or more that are black are the cylinders that need to have the injectors looked at.