Fans Stay Running

Real Car Repair Stories – The Fan Stays Running

2014 Chevrolet Silverado Fan Stays Running

In this edition of Technician Files we explain what happened to a 2014 Chevrolet Silverado when the fan stays running after you turn the key off.

Fans stay running

Our customer contacted us in December 2023 and stated that the fan on his truck continued to run after the key was turned off.  

We suggested they bring it in and drop it off for us to diagnose the issue it was having.  When the customer dropped of the vehicle he stated that the check engine light comes on and goes off sometimes as well.  

We let the customer know the diagnostic charge was just $89 for this issue and would give him a call when we figured it out.  LMC gave him a ride home in our courtesy shuttle and our technician got to work checking out the truck.


The Diagnostic

Fan stays running

When diagnosing an issue like this truck is having there are quite a few steps to follow to determine the cause.

First is to check the fluid levels and if ok and not low or leaking, test drive the vehicle.  This allows the technician to hear, feel and see how the vehicle acts.  After that the technician will attempt to duplicate the customers concern, in this case, the fan stays running after the key is turned off.  Yep, it sure does, the technician makes note of that and then proceeds to see if there are any trouble codes.  A scan of the engine computer revealed a diagnostic trouble code, DTC P0128 stored in its memory. This code definition is that the engine coolant temperature is below the thermostat regulating temperature.  Wow that’s allot of words, what does that mean in normal talk?  In basic terms it means that the engine is not getting warm enough nor fast enough.  

So now, the technician is armed with allot of information and needs to put all that together to formulate the diagnosis and repair.  

The next step is to understand the theory and operation of the cooling system on this vehicle because if the engine is too cold, why is the fan stay running?!  

So Chevrolet and some other manufacturers have programed these vehicle to turn the fan on and continue it for a few minutes after the key is off in order to ensure the safety of the engine.  Even though it is not getting warm enough, the computer is programmed to run the fan any time a cooling system problem is detected.  Therefor, the fan stays running after the key is turned off.  A good system, we don’t want to damage the engines if we can help it.  

So with this, when it determines the engine has a cooling system issue, the fan will stay running even after the key is off.  

Well, what is wrong with it?

The technician is going to find what would cause the engine to stay too cold and not warm up to normal operating temperature.  He will do this using varies tests, techniques and repair documentation.  Once he has figured it he will write up what repairs are needed. 

In this case, the engine thermostat was causing all of this trucks issues.  More information on P0128 code can be found here at AutoCodes.

So, not such a big deal replacing the thermostat to correct this issue.  The truck was repaired and another test drive afterwards confirmed that the repair was correct and the fans no longer stayed running after the key was turned off.  The customer was picked back up with our shuttle and another successful repair by the technicians at LMC Complete Automotive.  If you need help give us a call at 2816517766 or you can schedule service here.

LMC Complete Automotive