Nissan Repair: 2004 Quest, computer failure, mass airflow sensor, fault tree analysis

Question
we have had our 2004 Quest for 5 years and it has been running well.  Recently my wife paid almost $1000 to repair the rear brakes and she inquired about the engine light that was on- the van was running well.  The dealer ran diagnostics and advised that we would need to do some 3-4 K in work including replacing the computer and several sensors.  We opted to repair the brakes only and 2 days later the van would start, however the accelerator would not function.  We were told that the computer needs to be replaced etc.  It seems very coincidental that the van was running fine up until this point and now needs extensive repairs that we cannot confirm.  Thanks for your thoughts

Answer
Dave,

I would get a second opinion on the computer.  Most of the time the mass airflow sensor screws up and has to be replaced.  It is not often that the computer takes a dump.  Go to a different dealer and get a second opinion.  Or a private shop that deals with Nissan vehicles.  Do not tell the current shop where you are taking it.  If you are getting it towed use an independent tow service to get it moved.  You do not want the current dealer telling the next shop what they think they found.  $3K or $4K is over the top as costs go...  If you go to nhtsa.gov and click on service bulletins and drill down for your vehicle this is what I found for your car.  The following are service bulletins and are for yoru car.  If your car was still under warranty Nissan would have repaired them for free.  But, at least you have them and can address these with the mechanic.  Also, have the mechanic show you the fault tree analysis to prove the ECM is bad if he says it is bad too.

Make : NISSAN Model : QUEST Year : 2004
Manufacturer : NISSAN NORTH AMERICA, INC.   
Service Bulletin Number : 06075 Date of Bulletin : NOV 01, 2006
NHTSA Item Number : 10020932   
Component : ELECTRICAL SYSTEM:IGNITION
Summary :
DIAGNOSTIC TROUBLE CODE (DTC) P0300, STORED AND IGNITION COILS BLISTERED. *KB  

Make : NISSAN Model : QUEST Year : 2004
Manufacturer : NISSAN NORTH AMERICA, INC.   
Service Bulletin Number : 05037 Date of Bulletin : MAY 13, 2005
NHTSA Item Number : 10015840   
Component : ELECTRICAL SYSTEM
Summary :
MIL ON WITH DTC P1402 EGR OPEN CODE STORED. UPDATE *SC  

Make : NISSAN Model : QUEST Year : 2004
Manufacturer : NISSAN NORTH AMERICA, INC.   
Service Bulletin Number : 04090 Date of Bulletin : OCT 21, 2004
NHTSA Item Number : 10009365   
Component : ELECTRICAL SYSTEM
Summary :
MALFUNCTION INDICATOR LAMP ON WITH DIAGNOSTIC TROUBLE CODE P0300-P0306, P1273 OR P1283. *TT *SC  
Make : NISSAN Model : QUEST Year : 2004
Manufacturer : NISSAN NORTH AMERICA, INC.   
Service Bulletin Number : 04028A Date of Bulletin : MAR 24, 2004
NHTSA Item Number : 10005976   
Component : ELECTRICAL SYSTEM
Summary :
MALFUNCTION INDICATOR LAMP ON WITH DIAGNOSTIC TROUBLE CODE P1031, P1051, P1148, P1168 (A/F SENSOR HEATER / CLOSED LOOP) ON 5 SPEED AUTOMATIC TRANSMISSIONS ONLY. (THIS VERSION SUPERSEDES NTB04-028.) *TT  

Make : NISSAN Model : QUEST Year : 2004
Manufacturer : NISSAN NORTH AMERICA, INC.   
Service Bulletin Number : 04025 Date of Bulletin : FEB 19, 2004
NHTSA Item Number : 10006100   
Component : ELECTRICAL SYSTEM
Summary :
MALFUNCTION INDICATOR LAMP (MIL) ON P0171 / P0174 / P1273 / P1283. *TT  

Make : NISSAN Model : QUEST Year : 2004
Manufacturer : NISSAN NORTH AMERICA, INC.   
Service Bulletin Number : 03067A Date of Bulletin : OCT 22, 2003
NHTSA Item Number : 10003899   
Component : ENGINE AND ENGINE COOLING:ENGINE
Summary :
MALFUNCTION INDICATOR LAMP ON WITH DIAGNOSTIC TROUBLE CODE P1274/P1284 (A/F SENSOR BANK-1/2 RICH MONITOR). *TT