Grand Marquis

Check Engine Light Due to Failed Oxygen Sensor on Mercury Grand Marquis

Problem Description and Possible Solution

One or more oxygen sensors may fail resulting in illumination of the Check Engine Light.

Problem Data
RepairPal Verified
Average mileage: 119,905 (89,321–149,000)
5 model years affected: 1992, 1997, 1999, 2000, more2005
18 people reported this problem
Viewing 1 - 3 of 3 comments
slow to accelerate, runs rough, horrible gas mileage. Hooked it up to system and received engine error code p0171 and po174 cylinder bank 1 and 2.
The check engine light came on and the car runs rough on starting an accelerating and horrible gas milage. When checked came up oxygen sensors needed to be replaced.