Aviator 2WD V8-4.6L DOHC (2003)
Air Flow Meter/Sensor: Technical Service Bulletins
Engine Controls - MAF Sensor Diagnostic Service Tip
TSB 05-3-1
02/21/05
MAF DIAGNOSTIC SERVICE TIP - VEHICLES
EQUIPPED WITH EGR SYSTEM MODULE (ESM)
FORD:
2003-2005 Crown Victoria, Thunderbird
2005 Five Hundred, Ford CT, Freestyle, Mustang
2004-2005 Explorer, F-150, Freestar
2005 E-Series
LINCOLN:
2003-2005 LS, Town Car, Aviator
MERCURY:
2003-2005 Grand Marquis
2005 Montego
2004-2005 Monterey, Mountaineer
ISSUE
When diagnosing for a possible MAF sensor related condition, on a vehicle equipped with an EGR system module (ESM), an incorrect engine-running
BARO value is no longer a reliable indicator of a skewed MAF sensor. Vehicles with ESM use both the MAP and MAF for engine-running BARO
updates. Replacing the MAF sensor for a seemingly incorrect or inconsistent key-on BARO is not an effective repair for vehicles equipped with an ESM.
ACTION
Refer to the following Service Tips to aid in diagnosing MAF and other malfunction indicator lamp (MIL)/driveability concerns, using the BARO PID.
SERVICE TIPS
NOTE
SOME EARLY BUILT 2003 VEHICLES EQUIPPED WITH AN ESM MAY NOT HAVE THE STRATEGY/CALIBRATION TO UPDATE THE
BARO PID USING THE ESM'S MAP SENSOR. IN THESE APPLICATIONS THE BARO WILL BE UPDATED BY THE MAF SENSOR, OR IF
FAULTS ARE PRESENT A DEFAULT VALUE WILL BE SET (DEFAULT VALUE MAY DIFFER DEPENDING ON APPLICATION AND
STRATEGY). DIAGNOSE THESE APPLICATIONS WITH THE CURRENT PROCEDURES WITHOUT USING THE ESM'S BARO
METHODS.