This Preliminary Information communication provides information to the technician about vehicles may set an intermittent Diagnostic Trouble Code P2097. Technician will need to check freeze frame/ failure records to determine what the short term/ long term fuel trims were when the Diagnostic Trouble Code set. If the fuel trims were adding fuel then check for an aftermarket air filter, and intake system air leak, and restricted flow injectors. If the fuel trims are normal, check for that the post Oxygen Sensor heater and circuits are working. Also check for exhaust system leaks, can use Evaporative Emissions System tester to pressurize exhaust system and spray a soapy solution around the exhaust system joints looking for leaks.