Such things don't get repaired because of fault codes, they get repaired because the car won't run. How well does the car run? The engine actuator / aka throttle body can be rebuilt by Beckman Technologies in NC at 800-742-1021. It could also be just a bad harness for the engine actuator. If it was me I would not go back anywhere that had to cajones to give such an estimate. You should get a second opinion from an honest independent shop, or if the car is operating just watch the fault codes yourself.