Q: How do you know which cv joint is causing the noise

The noise could be from both sides and you might not need to decide, left versus right, if the rubber boots on the outer CV joints happen to be broken on both sides. The CV joint boots look like 4 inch long bellows and are on the outer ends of each CV axle. You can manipulate each boot to see if it is intact but if they are leaking usually you will see grease in the vicinity as well, that has flown out of the joint as the axle spins at high speed. If the boots are broken, and have been broken for a while, usually the grease gets out and water gets in and wears the joint, so basically if the boots are broken on both axles you just replace both axles. If the boots are still intact but you believe one or more joints are making noise, the mechanic can either listen for the noise and try to distinguish left from right or simple affix wireless mini microphones to each steering knuckle and drive the car around while switching channels between left and right. That makes pinpointing the noise easy.

If you request a front axle noise diagnostic, a certified mechanic from YourMechanic will investigate the noise you are hearing and pinpoint the origin. If one or both CV axles are defective, YourMechanic does remove and replace CV axles on a mobile basis. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.