Gas Recirculation Valve (egr Valve) problems of the 2007 Nissan Xterra

This complaint is in reference to a 2007 Nissan Xterra off road 4x4 with180,900 miles. The transmission began to spontaneously downshift to low gears while moving at speeds above 25 mile per hour. At one point, the transmission seized and locked up while traveling at 45 miles per hour, which resulted in a sudden stop in the midst of the traffic flow on a two lane road. I took the vehicle to the Nissan dealer for service immediately. Inspection revealed coolant had leaked into the transmission via a leaking transmission cooler assembly integrated into the main engine radiator. The transmission sustained substantial internal damage from the coolant mixing with transmission fluid and circulating through the transmission. The transmission and engine radiator had to be replaced in order to make the vehicle roadworthy again. Total cost of the repair with taxes was $4800. 00. Nissan service manager and techs at dealership indicated this is a common problem for the Xterra and frontier model vehicles, yet no proactive action was taken during previous service appointments at 30,000 mile service intervals, routine maintenance appointments, and during yearly state vehicle inspections conducted at the same Nissan dealership.

Transmission downshifted on its own at 45 on a mild downgrade. Did it again later changing from one four lane highway to another, this time around 45-50 mph. Took the truck to local Nissan dealer for diagnosis as I took out an extended warranty with olympicare. The service adjuster was aware that '05-'09, even '10 models have a defect that allows radiator fluid to mix with transmission fluid, creating degradation of transmission and cooling system. After-market warranty is trying to dis-allow claim, citing Nissan's knowledge of this design flaw.