P1131 FORD -

Question

Engine is now running rough

Answer 1

Hi there

This code indicates the bank 1 upstream O2 sensor is having issues with switching. This is pointing to a lean condition which can be caused by the sensor or possibly an issue with a vacuum leak.

Here is some more info.

P1131 FORD - Lack of Upstream Heated Oxygen Sensor Switch Sensor Indicates Lean Bank 1

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