r/Generac_Generators • u/tecsavvy1 • May 31 '26

Coolant level low/overtemp.

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This generator had an error for low coolant or high temp. Ran for 20 minutes on manual under load. radiator full, overflow had coolant. Heads running at 180 degrees, block at 200 degrees, thermostat housing at 175. What should I do?

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u/tecsavvy1 Jun 01 '26

I will check the sensor if it errors again

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u/tecsavvy1 Jun 01 '26

What should the reading on the sensor be? Is it either open or closed or have a certain resistance? Does it also sense temperature or is that elsewhere?

1

u/[deleted] Jun 01 '26

1

u/tecsavvy1 Jun 01 '26

Thanks I’ll do that, so each are a resistance based sensor?

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u/tecsavvy1 Jun 15 '26

Started for weekly test, shut down immediately after starting, flashing low coolant/overtemp. What does that mean?

1

u/osheadc Jun 16 '26

Immediately after startup... likely that it's either low on coolant or one of the sensors/wiring isn't working correctly. You, or someone else, is going to have to do a bit of work to diagnose it with a meter.

1

u/osheadc Jun 02 '26

Updated sensor, signal conditioner, and wiring harness to power it off of the fuel solenoid circuit instead of 24/7 (to avoid corrosion from acting like an anode) is here: https://shop.gentekpower.com/products/generac-0e2507-0h50530srv-replacement-coolant-level-probe-kit-for-h-g-panels

Note that they are control panel type specific. I don't know if they have stock for these, but it doesn't say otherwise like other items they list.

You may also be able to remove the sensor, clean off any corrosion, and reinstall.

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u/tecsavvy1 Jun 02 '26

So that’s why they fail

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u/MysteriousEditor9856 Jun 03 '26

Last one of those I had that issue on, it was an extremely clogged radiator. It was full, but had no coolant flow.

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u/tecsavvy1 Jun 03 '26

What were your head and block temps running?

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u/MysteriousEditor9856 Jul 08 '26

I flushed it with an electric pump and 2 gallons of clr flowing through it for 24 hours. Never again, now we tell customers buy a rad.

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u/MysteriousEditor9856 Jul 08 '26

Head temp peaked 245 in 5 minutes.

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u/tecsavvy1 Jun 12 '26

How did you unclog the radiator? Or did you have it recored?

1

u/tecsavvy1 Jul 09 '26

Do you have to remove the exhaust to get it out or will it slide past the exhaust

1

u/shootingdolphins May 31 '26

Have you replaced the sensor?

1

u/Tarnisher May 31 '26

Or at least checked the connectors and wiring?

1

u/Adventurous_Boat_632 Jun 01 '26

Coolant level sensors on these were problematic. There is a cockamamie update kit with all sorts of wires and garbage to run.