2005 Ford F150 Engine Fail Safe Mode

2005 FORD F-150
46,000 MILES • V8 • 4WD • AUTOMATIC
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TRPLT1
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What causes Engine Fail Safe Mode? Twice now I have experienced the truck switch into safe mode while driving. The dealership code the first time was a faulty transfer case motor, the second time no fault was registered.
Jan 28, 2009 at 4:52 PM
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DAVE H
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Failure Mode Effects Management
Failure mode effects management (FMEM) is an alternate system strategy in the PCM designed to maintain engine operation if one or more sensor inputs fail.
When a sensor input is determined to be out-of-limits by the PCM, an alternative strategy is initiated. The PCM substitutes a fixed value for the incorrect input and continues to monitor the suspect sensor input. If the suspect sensor begins to operate within limits, the PCM returns to the normal engine operational strategy.
All FMEM sensors display a sequence error message on the diagnostic tool. The message may or may not be followed by Key On Engine Off (KOEO) or Continuous Memory DTCs when attempting Key On Engine Running (KOER) self-test mode.
Jan 28, 2009 at 7:17 PM