SureTrack Community Fix: Is It Hot Or Not?

Real Fixes from Mitchell 1’s SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read on to see how SureTrack can help you correct issues that are not easily diagnosed using OEM information alone. SureTrack is available at no additional cost in our ProDemand product.

Mixed signals from a vehicle can be frustrating, such as having a message on the dash saying the engine is hot when it’s not. SureTrack community member sportsman850sp had a Buick Lucerne in their shop that would display “Engine Hot A/C Off” on the dash as soon as the vehicle was started cold. They posed the question to the community, and with the help of fellow community member dmckemie12, Richard_C and others, they were able to resolve the issue quickly.

The following Community Fix summarizes the interaction between members of the community that led to the solution.

2009 Buick Lucerne CXL 3.9L

Engine Hot message on dash, replaced thermostat.

Customer states that vehicle displays “Engine Hot A/C Off” message on instrument panel.

Diagnostic Steps Performed/Parts Replaced
Started engine cold and Engine Hot A/C Off message appears on instrument panel. Cooling fans running all the time. Looked at engine data and temperature reads 140 degrees F. Engine is not running hot.

Best Answer from Community Member dmckemie12
Check the ECM for DTCs, it most likely has a P0128 stored and needs a t-stat. If the P0128 was logged the previous drive cycle, upon the next ignition it gives a message of “Engine Hot A/C Off’ and disables the gauge and compressor. Even though the DTC is for the engine running too cool, and it knows it, it does that.

Bad thermostat causing car to run too cool even though giving message that engine was hot.

Replaced thermostat and cleared codes, message no longer displays.

SureTrack® adds to the power of ProDemand® with an exclusive combination of real-world knowledge and powerful diagnostic tools, all wrapped in an interactive community of professional technicians. Designed to help automotive shops increase accuracy and efficiency from diagnosis to completed repair, the industry’s most comprehensive repair information resource is just a few clicks away.

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About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.