Rusty Or Corroded Appearance On Exhaust Components - keywords corrosion muffler pipe rust

This PI was superseded to update model years and administrative details. Please discard PIT4351A.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

GM Engineering has investigated reports of a rusty or corroded appearance on the exhaust components for new vehicles being received at the dealer. During certain times of the year, vehicles being produced in Michigan may be exposed to road salt which is used to maintain roads in the winter months. This salt may be present on the plant premises, city streets around the plant, or on the transport truck. During transit between the plant and the dealer some of the exhaust components may corrode as a result of this salt exposure. These exhaust parts are made of a bare mild-grade stainless steel that will oxidize, or appear rusty. Over time, these components will have a uniform rust-like discoloration, which should be considered a normal condition.

These components have been tested to 10+ years in normal service and the Vehicle Technical Specifications stipulate that cosmetic corrosion on these parts, which are not easily visible to the customer, should be considered an acceptable condition. Customers should be assured that these parts, even though they may have cosmetic corrosion, will not wear out prematurely or have any type of durability concern occur.

This is a normal condition and these components should not be replaced for this surface or cosmetic corrosion.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.