One problem related to manifold/header/muffler/tail pipe has been reported for the 2002 GMC Envoy. The most recently reported issues are listed below.
The contact owns a 2002 GMC Envoy. While driving approximately 45 mph, smoke and flames emitted from under the hood. The contact was able to exit the vehicle and with assistance, the flames were extinguished. There was no personal injury. The vehicle was towed to an independent mechanic who advised that the failure was contributed to the wiring harness being positioned too close to the exhaust manifold. The vehicle was in the process of being repaired. The manufacturer was notified of the problem. The approximate failure mileage was 137,000.