I read an article - Best to test accuracy before install , but I did not ... so , my question is how to test without removing probe - to get an idea if accurate . Probe is behind the water inlet neck on manifold ( where stock sender was ) if I take reading of IR gun on the metal sender or say the hose or neck , should they be close to reading on gauge ? Point of this is to determine why my car reads hot ( mainly when A/C used in city crawl ) article said Stewart Warner gauges can be off - “ We used the boiling water test to check the Stewart Warner gauge in question, and with the probe in boiling water the gauge displayed approximately 235 degrees F! During a phone call to Stewart Warner in hopes of getting a replacement gauge, the author was told “Not to worry; that model of gauge is only accurate to plus-or-minus 14%.” Well that’s a handy explanation, since at actual 200degrees coolant temperature a 14% error would cause the reading to be 28degrees in error! We might as well not even have a coolant temperature gauge if it cannot be more accurate than those measurements.“