SureTrack Community Fix: Conflicting Messaging

Real Fixes from the 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 currently available free with the purchase of a current Snap-on® diagnostic software version.

Sometimes being too cool is a bad thing, even though your dash is saying you’re too hot. SureTrack community member harristech had a Chevrolet Silverado in the shop where the A/C would stop working and the instrument cluster had a message about the engine being too hot. They posed the question to the community, and with the help of fellow community member Dmckemie12 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.

Vehicle
2007 Chevrolet Silverado Classic 1500 4.3L

Title
Code P0128, replaced incorrect thermostat.

Complaint
Customer states that A/C shuts off and message on dash says the engine is hot.

Diagnostic Steps Performed/Parts Replaced Ran truck 10 miles. has code P0128. Dash board shows “A/C off, Engine Hot” message. Vehicles coolant is topped off. With scan tool, engine temp is showing 170 degrees though. The temp gauge in dash drops all the way down when the code sets. Replaced coolant temp sensor, still same symptoms. Run vehicle in shop, everything works fine. But as soon as you test drive, all symptoms return after about 10 miles. What could be the possible problems?

Best Answer from Community Member Dmckemie12 The ECM flagging the DTC is causing all of that. When it logs the P0128, it disables the gauge, the A/C compressor, and puts the message on the DIC. Don’t ask me why. The DTC is for the engine running too cool, and it knows it’s not overheating.

Cause
Removed thermostat and found that it was a 170 degree one instead of the required 195 degree.

Correction
Replaced thermostat with correct 195 degree one, test drove vehicle and symptoms did not return.


SureTrack® is a powerful value-added feature available with select Snap-on diagnostics tools. It offers an exclusive combination of expert knowledge and detailed parts replacement records, all wrapped in an interactive community.

Want more? Click here for more information on using SureTrack.

New or Expired SureTrack users: Click here for authorization key instructions.

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.