A Redditor was in for a nasty surprise after bringing his 2020 Toyota Corolla to a mechanic for a simple coolant leak. The shop quoted him $10,116.27 for parts and labor. He took the estimate to the “Ask A Mechanic” forum and received a wide range of responses.

First and foremost, the mechanic believed the coolant leak caused an electrical short. The result: “Wire harness connector is fried.” The estimate called for replacing the ECU, an expensive component, and the vehicle’s entire wiring harness. That is a time-intensive repair.

The mechanic’s message read, “You are looking at $10,116.27 for labor and parts.” The quoted cost of parts was $6,066.27. Labor was estimated at 15 hours for $4,040. All of this was for a Toyota that was three years old at the time.

The owner’s response was simple: “O my.” Understandable. He asked the mechanics of Reddit, “Is this even real? Why so expensive?”

Why wiring harness repairs get expensive fast

Commenters made several important points. Troubleshooting an electrical short is notoriously difficult. A modern wiring harness contains thousands of individual wires and connections. Because of that complexity, many shops avoid deep diagnostics.

One now-deleted commenter wrote, “Usually when a shop tells you a car needs a whole harness, they don’t know what is wrong and are hoping you won’t approve the repair.”

In some cases, paying a mechanic to carefully track down the fault may save money. However, others cautioned that coolant contamination changes the equation. One mechanic explained, “If it’s bad cause of a coolant leak there’s no way to know how much the rest of the wiring is contaminated. coolant will wick itself through the wiring.”

Another commenter agreed. “Coolant enters the harness from a thermostat heater or coolant temp sensor, then migrates all the way to the ECM.” That possibility makes partial repairs risky.

So was the Corolla owner stuck with this massive bill? Yes and no. One commenter noted, “I just know a wiring harness is meticulous work. Not to say that it’s worth the price, but that 15 hours of work sounds about fair.”

Others focused on the labor rate. A $4,040 charge for 15 hours works out to about $270 per hour. One response summed it up bluntly: “Dealerships don’t even charge that much.” Another added, “This shop just doesn’t want to do the work, so they’re making the bill so expensive that the customer will refuse.”

Several commenters suggested sourcing a cheaper wiring harness. “See if you can find a harness at a junkyard or see if they’ll give you part numbers and order it online.” That approach has downsides. Many shops refuse to install customer-supplied parts. Used wiring harnesses also come with their own risks.

As one commenter put it, a junkyard harness may make sense for an old project car. It may not be ideal for a three-year-old daily driver.

The most consistent advice was also the simplest: “Call around and ask a few shops what they’d charge for this job.” You can see the original post embedded below:

What do I do? it’s more than half value of my car.
byu/fook07 inAskAMechanic