What is the cost to repair a a transmission sensor in a 04 Mit. Galant

What is your question?

We were told $551 to replace the fluid and sensor. The car was pulling as strong as before. It does have high mileage and we can’t afford to replace the trans. Right now

What makes this problem better or worse?

Driving

How long has your 2004 Mitsubishi Galant had this problem?

2 weeks