Hello and welcome, Super mechanic here. I will do my best to help you with your question.
Is it toward the rear of the vehicle or the front?
What state do you live in?
Have you owned it since new?
Infiniti has determined that a defect that relates to motor vehicle safety exists in some 1997-2001 model year Infiniti QX4 vehicles. The fuel filler tube may have an insufficient amount of coating at the lower mounting bracket. If there is insufficient coating corrosion may occur in geographic areas that regularly use road salt in the winter. This corrosion can result in perforation of the fuel filler tube and fuel leakage. If there is fuel leakage in the presence of an ignition source a fire can result.
In order to prevent this potential condition Infiniti is conducting a Voluntary Safety Recall Campaign to replace the fuel filler tube assembly in states that regularly use road salt in the winter and to inspect and if necessary replace the fuel filler tube assembly in states that are not listed as ones that regularly use road salt in the winter.
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