1994 MERCURY MARQUIS
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ANTDOGGDAREALIST
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  • 2 POSTS
I got a guy to change my oil pan,now it will not stay running.Will run with MAF sensor unplugged,changed it same thing.MAF sensor can be plugged up,and take off air intake hose it will run.Both ways the car runs rough.What can be wrong?Help! 998 code Hard fault FMEM engaged.
Oct 19, 2012 at 3:02 PM
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KHLOW2008
  • AUTOMOTIVE REPAIR CONTRIBUTOR
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FAILURE MODE EFFECTS MANAGEMENT
(FMEM) CODE 998

FMEM mode allows system operation when sensors fail or transmit signals that are out of normal operating range. During FMEM mode, PCM substitutes a mid-range signal for defective sensor while continuing to monitor sensor. If faulty sensor's signals return to normal operating range, PCM will use those signals. A Code 998 will be displayed when FMEM mode is in effect.


Disonnecting the MAF etc could have triggerred this. Clear the code and retest and see what code comes up.
Oct 19, 2012 at 5:48 PM