Q: Strange loud squeal

Downloading the diagnostic code(s) that have caused the check engine light to illuminate will probably provide a major clue as to the origin of the noise. A check engine light diagnostic can be requested to deal with that and, at the same time, the origin of the noise would of course be pinpointed and diagnosed. If you are hearing the noise at idle when the car is not moving, generally the noise you are describing originates in the engine, the transmission (torque converter runs even at idle), and/or the accessory drives. If the origin of the sound is not obvious (pinpointed) on the mechanic’s initial inspection, a quick diagnostic can be performed by simply taking all of the belt driven accessories out of the picture by disconnecting the drive belts and then very briefly running the engine. If the sound disappears, the faulty component is then isolated amongst the accessories and pulleys. If the sound does not disappear, that means the noise originates within the engine and/or transmission. If you request either the check engine light diagnostic or a vehicle noise diagnostic a certified Mechanic, dispatched by YourMechanic right to your location, will get this resolved for you (either service will get you to the same end point which is a repair of your vehicle). If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.