code 1131 on 1999 Mercury Mystique

What does code 1131 most likely mean?

by in Omaha, NE on August 11, 2009
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1 answer
ANSWER by , August 11, 2009
The OBD-II P-1131 means: Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1.