Generac Generator Error Code 1801: How to Fix High Coolant Temperature

Q: Can I continue running my Generac generator with error 1801?

No. Error 1801 indicates high coolant temperature, and running the generator can cause severe engine damage. Always shut down and address the issue immediately.

Q: How often should I check the coolant level in my Generac generator?

Check the coolant level every 50 hours of operation or at the start of each season, as recommended in the owner's manual.

Q: What type of coolant does a Generac generator use?

Generac recommends a 50/50 mixture of ethylene glycol antifreeze and distilled water. Some models require a specific coolant type; check your manual.

Q: Why does my Generac generator keep showing error 1801 after I added coolant?

The issue may be a stuck thermostat, blocked radiator, faulty water pump, or air in the system. Follow the troubleshooting steps above to pinpoint the cause.

Q: Can a dirty air filter cause error 1801 on a Generac generator?

A dirty air filter can affect engine performance but typically does not directly cause high coolant temperature. However, it is always good practice to replace or clean the air filter regularly.

Abstract

Error code 1801 on your Generac generator indicates that the engine coolant temperature is too high. This critical error triggers an automatic shutdown to prevent engine damage. The most common causes are low coolant, a faulty thermostat, a blocked radiator, or a failing water pump.