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Q: The service 4WD/Service Engine Soon Light is on, and my car has front end noise.

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I have a 2002 GMC Envoy SLT. My Service 4WD light has been on for a while but my mechanic didn't seem too concerned about it when it was in the last few times. Recently, my service engine soon light turned on, as well as a small blinking light relating to my A4WD and I've had a front end noise that sounds like rattling, doesn't really start until the vehicle gets up to about 40mph. Any idea what could be wrong and if I'm safe to continue driving my car until I can get it to the mechanic again?

A: Hi and thanks for contacting YourMechanic. ...

Hi and thanks for contacting YourMechanic. This sounds like the front differential has medal particles in the gear assembly, and if so, you will have to remove the differential and have it diagnosed from the inside to see what bearing has failed. Most likely, the final drive thrust bearing came apart needs replacing along with any other parts that are damaged.

If you need further assistance diagnosing your vehicle, then seek out a professional mechanic, such as one from YourMechanic, who can come to your location to determine why the service light is on and suggest any necessary repairs.

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