Car Temperature Gauge Stopped Working?
You’re driving your car and notice that the temperature gauge has stopped working after a few minutes of driving. Or maybe it just stops suddenly. Is your engine on the verge of overheating? Is it a simple malfunction that can be fixed quickly, or will it require a costly repair? Learn more about what causes a temperature gauge to fail, whether it’s safe to continue driving, and how to diagnose the problem.
How temperature indications work
A typical thermometer in a car works as a thermistor, changing its internal resistance in a circuit depending on the temperature of the heated surface to which the probe is attached. The resistance in this circuit is high when the monitored temperature is low, but drops significantly as the temperature increases.
Usable feedback is obtained by supplying a defined input voltage (5 V) to the engine’s ECT (Engine Coolant Temperature) sensor.
When the motor is cold, this voltage is opposite to the nominal value. With heat, the resistance of the circuit decreases, resulting in higher nominal power. The output signal from this sensor is read by the vehicle’s computer (ECM or PCM) and displayed on the affected vehicle’s instrument cluster.
It’s also worth noting that feedback from the engine coolant temperature sensor is used to calculate vital operating parameters such as fuel and ignition timing.
So don’t think that a failed engine temperature gauge is a big deal; engine performance will certainly suffer if this feedback is lost. Causes of Poor Temperature Display
A vehicle’s temperature gauge can fail for a variety of reasons, some of which are much harder to isolate than others. Those familiar with such causes are usually very skilled at diagnosing and fixing such issues. Here are some of the most common causes of car temperature gauge failure:
1) Coolant Temperature Sensor Failure
As mentioned above, your vehicle’s coolant temperature sensor is responsible for measuring the engine temperature while you’re driving. This sensor is usually located very close to the engine’s thermostat, making it a relatively common failure point on most engines. If defective, your vehicle’s temperature sensor may not record feedback as normal.
2) Damaged ECT Sensor Wiring
Damaged wiring in your vehicle’s engine coolant temperature sensor circuit may also cause the temperature gauge to appear inoperable. This is especially true if the feedback wire in the circuit should be “open.” In this case, you may also notice your vehicle recording a new Check Engine Light illuminate.
3) Stuck/Broken Display
Though rare, a stuck needle can cause display issues, such as the display not moving or becoming inoperable. In many cases, the instrument cluster of the affected vehicle must be removed and repaired (or overhauled).
4) ECM/PCM failure
Another rare cause of temperature gauge failure is a damaged ECM/PCM. The vehicle’s ECM/PCM is responsible for interpreting the feedback from the ECT sensor, so the condition of this module must be satisfactory for the display to function properly.
However, before questioning the ECM/PCM, all other possible causes of this type of problem should be thoroughly investigated. Although it does not happen often, if the ECM or PCM is truly at fault, the cost of replacement and reprogramming often exceeds $1,000. Is it safe to continue driving?
Most vehicles can be driven without a working temperature gauge, but extreme caution should be used when doing so. This is because visibility of the engine temperature gauge is critical to efficient and responsible vehicle operation.
If you fail to detect rising engine temperatures and act accordingly, you risk causing serious damage to your engine. Additionally, the operation and overall drivability of your vehicle may also be affected if you do not have a visible digital or analog temperature display.
The engine coolant temperature gauge is very important to the operation of the entire engine. If it is missing, it often leads to poor or degraded engine performance. If the ECT sensor is faulty, your vehicle may not even start under certain conditions.
In either case, the root cause of your vehicle’s temperature gauge failure should be diagnosed and addressed as soon as possible. This may prevent future engine damage and reduce the risk of associated drivability issues. If you are unsure whether you can repair it yourself, it is best to take it to a trusted repair shop as soon as possible.
Diagnosis and Repair
The following steps can be used to diagnose and repair the root cause of an engine temperature gauge error. As always, it is best to consult the factory specific service literature for your vehicle model before attempting such a repair.
#1 – Check for Error Codes
Before delving into the diagnostic process itself, you should use an OBD-II diagnostic tool to check for active diagnostic trouble codes. Any existing faults should be thoroughly diagnosed before proceeding.
#2 – Check the Current Temperature Readings
The same holds true here. Use a quality diagnostic tool and check if there is any feedback from the ECT sensor immediately after driving for a short period of time. If these values ​​are within tolerance compared to the vehicle manufacturer’s specifications, then the focus should shift to checking the integrity of the vehicle’s instrument cluster and associated circuits.
#3 – Check the ECT Sensor and Wiring
If previous tests have shown that the temperature sensor readings are problematic, then a close visual inspection of the coolant temperature sensor and associated wiring should be performed. Look carefully for any obvious signs of damage to the ECT sensor and check the condition of the connectors as well.
All associated cables should also be manually traced and thoroughly inspected. Under the hood, you should also ensure that the engine coolant is properly topped off.
#4 – Test ECT Sensor
If no visual signs of damage were evident, your vehicle’s ECT sensor needs to be checked, in accordance with applicable factory-specific service literature for that vehicle.
This type of testing will require inlet/outlet voltage checks, as well as resistance testing across the sensor itself. Any condemnable readings will ultimately necessitate ECT sensor replacement.
