Nissan Repair: Check engine light on 2001 Nissan Sentra, nissan sentra, oxygen sensors

Question
The code says O2 sensor bank one, this was replaced, check engine light comes on again after several miles, it may go all day and then come on or it may be off several days and then come on.  Air filter and sensor has been checked.  Any help would be greatly appreciated.

Answer
Jerry,

If you replaced all the oxygen sensors (and I would replace them all together to get a baseline)  And, the car is still throwing an oxygen sensor code it means that the car is unable to get the exhaust under control.  It could be a stuck injector or a fouled sparkplug.  I would check the fuel pressure while running and with the engine turned off.  If the pressure drops off quickly then you have a leaky injector.  Pull the plugs and if any are exceptionally black you found the hole with the leaky injector.  In any case I would change the plugs so this will let you know if you have a leaky injector.  Email me back with what you find.