Bad engine

^
Very true, but one presumes that a radiator hose failure would result in a pretty significant pulse of steam whose immediate action is just about always an immediate engine shut down.

Also....modern vehicles also have pretty, flashing lights to draw the eye towards a system malfunction.

 

I guess the point was that there might be nothing in that situation to set off the pretty flashing lights. The immediate engine shutdown would need to be your immediate reaction to the sudden blast of steam.

... which was pretty much my Dad's reaction that time I left the radiator cap on his Vega not quite properly secured.

That car had a front-hinged hood, so when the cap let go, the steaming coolant all sluiced up onto the windshield, making it pretty hard to miss.

 

Easy enough to add these days through the OBDII port

 

Having a scangauge constantly connected, I started getting "Check Hybrid System" warnings, and work-to-rule brake behavior. Local dealership checked it over various times, and final suggestion was to try disconnecting the SG. Did the trick, but no more coolant temp for me.

Bottom line: yes, you can cobble an aftermarket gizmo, but please Toyota, bring back the built-in coolant temp gauge.

 

I have to chime in that such a ScanGauge experience is not universal; I'm in my eleventh year of a constantly connected ScanGauge with no such issues.

I did, however, confirm very reproducible issues of a similar nature when there was electrically poor pin contact, though. (I had a different device, not the ScanGauge, where the connector pins were not gold-plated.)

 

Yeah the mechanic (aka tech guy) had Techstream connected, and he noticed his connection was dropping occasionally, especially if he wiggled the plug. So maybe my knee had bumped it one time too many, who knows.

 

I guess it rankles too: go back 20 years, pretty much every econobox car managed to have a built-in coolant temp gauge. And H/V controls you could operate WITHOUT taking your eyes off the road.

 

So many head gasket issues in gen3 could have been avoided If we were aware of high coolant temp evolving.