Skip the auto shop - Our mechanics make house calls

Q: Message on my dash where speedometer is says ac off becasue engie temp is too high

asked by on

I got a message today that said my ac is off because engine temp is too high and my temp gauge doesn't seem to be working, it shows all the way cold. When I shut my car off it sounds like the fan or something is still running. I am wondering if this could be my thermostat.

My car has 107000 miles.
My car has an automatic transmission.

A: It sounds as if your car has put itself int...

It sounds as if your car has put itself into a default mode to protect itself form overheating. The fact that the gauge shows it is cold indicates there is likely a problem with the coolant temperature sensor. When this system fails, the PCM (powertrain control module) assumes the car is overheating to protect it from getting too hot and damaging the motor further. The A/C condenser is mounted on the front of the radiator and adds heat to the cooling system, so it is turned off to limit any extra heat sources from contributing to the lack of ability to cool the car sufficiently.

I would begin diagnosing this by connecting a scanner and inspecting the data. Most likely you will see the CTS (coolant temperature sensor) has failed. Keep in mind, wiring to the CTS could be damaged and causing this problem as well. The CTS data should show a temperature that reflects the temperature of the motor. If you have been driving it recently, it will be in the 180F to 200F degree range. If you check the data with the engine cold, the data should reflect the ambient temperature. It is common for a failed sensor to show a reading of -40 degrees Fahrenheit. If you want to have the AC system and related components inspected, a technician from YourMechanic can come to your home or office to diagnose your car and let you know what needs to be repaired.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Problem with valve injectors.

There quite a few things that will need to be checked. Fuel pressure and fuel pump volume need to be looked at along with a fuel sample. Incorrect fuel pressure or low fuel volume will effect the amount of fuel...

Q: What could be cuasing my problems?

Hi there. Rain or condensation can cause havoc with many electrical systems; especially if there are exposed wires or components that are getting wet. This can cause short circuiting situations and gauges to "act weird" like you're describing. As...

Q: How do I shift out of P (Park)?

You need to shift out of P (Park) and into a gear in order to start driving. Here’s how: 1. Turn on the vehicle. 2. Apply the brakes fully. 3. Press the button on the shift lever and hold it...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.