There are many things drivers don’t want to hear from their mechanic. “Sorry, it’s your transmission” is certainly one of them.

Even if it’s repairable, a transmission problem is likely to come with a hefty price tag.

Transmissions play a critical role in your car’s ability to operate. They carry the engine’s power to the drive axle by using different gears, which allows the engine to rotate at various speeds.

Let’s look at some of the costs of transmission problems and maintenance.

Transmission leak

One of the most common maintenance issues is low fluid level caused by a transmission leak. Because transmissions are sealed, a leak indicates a problem. Common causes of leaks include a breach in the pan gasket, an axle seal leak and fluid seepage.

Transmission fluid is typically bright red, dark red or brown as it ages.

If you notice fluid under your car, you should have the transmission checked by a mechanic.

The cost to repair a leak is typically between $150 and $200, depending on the car’s make and model, says Craig Douglas, president of Automotive Service Group in Indianapolis.

Solenoid problems

Douglas says a “middle-of-the-road repair” is replacing shift or pressure control solenoids.

Transmission solenoids control the flow of fluid in and around the transmission and operate through a voltage supplied by the transmission computer. Trouble shifting or over-shifting is a sign your vehicle’s solenoids need replaced.

A typical replacement cost is $300 to $850, depending on how many solenoids are replaced, Douglas says. But prices can vary greatly depending on the type of vehicle.

“It’s a good idea to do all of the solenoids while we are inside the unit because they are the same age and mileage and very labor-intensive to get to,” Douglas says.

Transmission flush

One of the only maintenance items you can perform on a transmission is a flush, which replaces old transmission fluid with new fluid. Signs your car many need a transmission flush include problems shifting gears and gears that are slipping.

Douglas says the average cost of a flush is $100. Sean Avner, owner of A Team Transmissions in Columbus, Ohio, recommends a flush every 20,000 to 60,000 miles, while Avner recommends the service every 100,000 miles, adding flushes are less important in newer vehicles.

Rebuild or replace the transmission

Avner says a minor leak can turn into a major problem if left alone. A low transmission fluid level or various component failures of the transmission can severely damage a transmission, leading to the need for a rebuilt or replacement transmission.

“Ninety percent of failures are caused by items inside the transmission that can’t stand the wear and tear of 80,000 or 90,000 miles,” Avner says.

Avner says the average cost of a rebuilt transmission is $2,800 to $3,800, and the average cost of a replacement transmission is $4,000 to $8,000.

Randy Hartman, owner of Herndon Reston Transmission in Herndon, Va., says the average cost of a rebuild is about $2,800 with the average cost of a replacement transmission costing $3,300 to $3,800.

Douglas recommends a used or remanufactured transmission over a rebuilt one. He says remanufactured transmissions often come with warranties from the manufacturer and the repair will go much quicker.