There's to sensors, one for gauge and one for ecm. I assume warning light comes on when ecm sees high temp. Gauge in peterbilt is pretty well known to be inaccurate. I run a scangauge so I see the temp ecm sees. Never had much luck with dash gauge working well.
Is fan kicking on? Is radiator dirty?
Fan kicks on for water temp at 217.
Blew radiator out yesterday and running at normal temp now, which I figured was the issue. Should’ve phrased my question better. Was asking more about fixing the gauge than what was causing truck to get hot. Thanks for the replies