Nissan Repair: SRTs 98 Nissan altima, fault tree analysis, nissan altima

Question
98 Nissan Altima 2.4 readiness monitors will not  reset ( O2, O2 heater, EGR ) have replaced O2 sensors and manually checked EGR, replaced battery, have driven the car over 250 miles am at wits end any help would be appreciated thanks Rich

Answer
Rich,

If you have replaced the battery the computer has had time to reset so we will go on to the next item.  You replaced both 02 sensors and have checked the EGR.  I would bet the EGR is defective and you should look at the connectors for the oxygen sensors first and then reset the computer.  If it does not clear the codes and go into readiness then you are looking at the computer being defective.  That is a chunk of change so I would be checking everything else first.  Also, disconnect and reseat the computer from the harness, with the battery disconnected.  Wait five minutes and then reconnect it and hook the battery back up.  If all of this fails then it is the computer.  If you want more specific advice about fault tree analysis go to nissanusa.com and download the specifics for your car.  it only costs $20 bucks for an hours of access to the .pdf files for a specific vehicle and it really helps.