Trouble with check engine light every time I drive the car on 1994 Mercury Grand Marquis

Check engine light keeps coming on. Every time I drive the car. Advised by the mechanic that the sensor light needs replacing What would the cost be for this.

Asked by for the 1994 Mercury Grand Marquis
1 answer
Hard to tell which sensor they are talking about, But its usually the oxygen sensor and you can check that price here and get another opinion here