Having problems with your 1998 Mercury Mountaineer ?
91000 miles; check engine light just came on?
Have your truck checked out with an OBD II scan tool. This tool hooks up underneath the drivers side steering wheel and will obtain the exact error code that will tell you what part has failed. This scan tool is avalible to use for free at your local auto parts store. Based on your mileage of 91,000 I would say the oxygen sensor has failed
Repair Help & Product Troubleshooting for 1998 Mercury Mountaineer
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