my fail safe light come on due to a broken crank sensor replaced sensor cant get fail safe mode to come off
Mercury Q&AAsk Your Question
2004 Mercury Mountaineer Question: fail safe mode light on
Answer #1dandd August 06, 2009, 16:41Master
If your Mercury only needed a Crank Sensor and nothing else, then the light should go off in about 2-3 days of driving. If you don;t have a scanner, then you can try disconnecting the battery for about a minute. If the light does not go off, then you have more than one problem, or the sensor was not installed properly or it was a cam sensor and not a crank sensor problem. ( common on Ford/Mercury ).