Q: Temperature guage fluctuates between mid temp (normal running) and cold at higher speeds

asked by on December 07, 2016

The vehicle sat idle during the Arizona summer months. When I started to drive it again in November the temperature guage came up to normal operating temp (mid guage) when idling. When at higher speeds the temperature drops and bounces off the bottom of the guage. I think the thermostat is stuck open. Will this damage the engine if I continue to run it like this.

My car has 103000 miles.
My car has an automatic transmission.

Thermostat Replacement $157.20 - $759.78 Get a Quote

This may cause other engine problems relating to the engine not warming up properly to run at normal operating temperature. There are many other systems that run based upon engine temperature and coolant temperature. Fuel injection and timing for example, is dependent upon engine and coolant temperature in order for it to properly supply the correct amount of fuel and ignition timing. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your thermostat.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Starter issues.
There are many problems that will prevent a vehicle from starting intermittently. If the engine doesn't crank at all, you have a problem with the starting/charging system or the engine is seized. If the engine cranks normally but doesn't start,...
How do I turn on the headlights?
The headlights are controlled with the Headlamp Control knob. To turn on the headlights, rotate the knob to the headlight position.
Emergency brake in 2006 Jeep Grand Cherokee stuck
Hello. If your Jeep feels like it is slowing down on its own, then the brakes may be binding. It may have to do with the parking brake or it can be something else. I would typically get the vehicle...
Missing and popping under heavy acceleration.
Popping back through the intake, along with misfires, is a sign that the engine is running lean (not enough fuel). Here are a few things to check: Check the fuel pressure: There is usually a port on the fuel rail....
My car is not starting when the MAF sensor is plugged in - 1991 Nissan Serena
This may be a sign of a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected...
My car's tire pressure light won't turn off
Unfortunately, this is a tough battle when it comes to the tire pressure monitor sensors and large fluctuations in weather. For every 10° drop in air temperature outside, your tires will lose about 1% in PSI or inflation. As you...
Heater blows out cold air 2006 Nissan Xterra
Hello - the lack of heater function could have 5 causes: the engine is not getting up to correct temperature (center of the gauge) due to a malfunctioning thermostat (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-thermostat), the heater control valve (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-heater-control-valve) is not letting hot coolant...
Just replaced ignition coil went to drive my 1991 dodge ram d150 and then I lost power to my accelerator.
Hi there. Although a physical inspection would be required to confirm this, based on what you have described, it's quite possible you experienced a backfire, which might have caused damage to the throttle body and even the linkage. If the...
Will using the brake pedal to reset the SBC counter work?
Good day Chibuikem, Thank you for contacting us today. We typically stick to the OEM repair tips and service ideas. According to MB, the right way to resolve this problem is through computer reset procedures - using an OBD-II diagnostic...

Related articles

How to Buy a Good Quality Thermostat
While While many people are familiar with the major parts in their vehicle, there are all kinds of smaller parts that play a vital role as well. The thermostat is one of those parts that many don't think about, but...
Symptoms of a Bad or Failing Thermostat
Common signs include the temperature gauge reading being very high or changing erratically, engine overheating, and coolant leaks.
How to Get Geo Dealership Certified
Geo car dealerships offer automotive technician jobs to mechanics who are Geo certified through the Automotive Service Educational Program.