1993 Pontiac Bonneville troubleshooting

[quote:1d2e69ba0e="dawoman1200"]Other Category problem
1993 Pontiac Bonneville 6 cyl Two Wheel Drive Automatic 170,00 miles
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When the car is sitting still at a stop light etc, the temperature gauge will go to over 120 degrees, but when on highway the temperature gauge stays where it should be and the heat seems to get warmer. What would this indicate as to the problem ?[/quote:1d2e69ba0e]
check coolant system and coolant fan
also flush the system then change thermostat
fill with new coolant
make sure fans working!