Are you having problems with your coolant temperature gauge staying on cold, even if the car engine obviously is warm?
One of the most important things to keep track of in your car is the coolant temperature because some horrible things can happen with your engine if it overheats.
In this article, we will talk about the coolant temperature gauge and what you can do if this issue occurs.
What are the causes of a car temperature gauge staying on cold?
The most common reason your temperature gauge staying on cold is a faulty coolant temperature sensor. It can also be caused by bad wirings between the cluster or the sensor. In some cases, it can also be a stuck thermostat causing the engine not to heat up properly.
Let’s go a little bit more into detail about the different causes. Here is a more detailed list of the most common causes when a temperature gauge stays on cold.
7 Causes of Car Temperature Gauge Stays on Cold
1. Faulty Engine Coolant Temperature Sensor
As we talked about, the most common problem with a faulty engine temperature reading is the coolant temperature sensor itself, sending the information to the cluster.
Some cars have two temperature sensors, while other car models have one. The models with one sensor usually both use the engine control unit’s temperature and the same sensor for the gauge.
If your car model has two coolant temperature sensors, one is used by the temperature gauge, and one is used for the engine control unit.
Engine temperature sensors are easy to measure with a multimeter, but you need to find the right values for them. You can often find more information on how to test them in your repair manual.
However, if you decide to replace one of them, you should make sure that you replace the sensor going to the temperature gauge – if you have two.
2. Broken Wirings
If you have two temperature sensors on your car and one separate for the gauge, you need to check the sensor’s wires to the gauge or ohm measure the sensor from the cluster connector.
If you have one sensor for both of them, there could either be a problem with the wires between the sensor and the ECU (most likely) or a wiring problem between the gauge and the ECU. Check for any broken wires between these components.
The best way to find broken wiring is to measure the resistance with a multimeter from all the wires’ directions. However, this requires a bit of electronic car knowledge, and you may have to let your mechanic take a look at it.
You can also find information about this in your repair manual. Check a wiring diagram of your car to measure the wiring correctly.
3. Faulty Gauge/Cluster
The next problem is a faulty temperature gauge. However, most temperature gauges are integrated with the instrument cluster on modern cars. In some cases, you can replace the temperature gauge or repair any bad solderings if you find any.
In other clusters, you might have to replace the instrument cluster. You can often leave your instrument cluster to an expert to repair the soldering if you do not know how to yourself.
A faulty cluster is not a very common problem, though, and they are often pretty expensive and need coding after replacement. Therefore it is recommended to check the other things first before you decide to replace the cluster.
You can also test the cluster temperature gauge with an Ohm tester if you have some knowledge.
4. Corrosion in plug connectors
Corrosion in the connectors is also a common problem when it comes to a faulty temperature gauge. Clean and spray electronic cleaner in the connector at the sensor, the engine control unit connector and the cluster’s connector.
If corrosion appears, there might be a problem with the connectors’ sealings, and you may have to take a look at these to make a permanent repair or replace them to avoid future problems.
5. Bad Thermostat
The thermostat restricts the coolant from flowing through the radiator. If this gets stuck on wide open, the temperature might not reach the optimal temperature.
However, this will often make your temperature go up a bit from the min mark if you drive hard enough. If your temperature gauge is going up slowly, you might have a problem with the thermostat.
You can read more about thermostats here: Faulty Thermostat Symptoms & Causes
6. Air in the Cooling system
Air in the cooling system can also cause the temperature gauge to stay cold if there is an air bubble right at the sensor spot. This can also often be indicated with a fluctuating coolant temperature gauge.
If you suspect air in the coolant system, you have to bleed your coolant system with a unique bleeding technique. If you want to learn more about this, you can check out our guide: Coolant Bleeding.
7. Broken Engine Control Unit
This only applies if your car uses one combined temperature sensor with two pins.
In some rare cases, your engine control unit could be a problem if the temperature information is received first to the ECM, which therefore sends the data to the cluster.
If this is the case, you have to check the trouble codes with an OBD2 scanner in the engine control unit to see if the engine control unit receives the temperature information.
If you can find the temperature readings in the engine control unit but not at the cluster, you have to make sure that they are using the same sensor. If this is the case, you have to measure the temperature output on the engine control unit. To do this, I recommend letting a car electronics expert do the job for you.
You do not want to replace the engine control unit if there’s no problem with it because they’re often costly and require coding.
Hazel Kay Mayfield
I have a 2011 mazda cx9 i replaces valve cover gaskets and coil packs now the temperature gage reads cold whwn running and 1/2 way when car is not running but key on the on position what could be the problem??
Doris Beavers
I have a 2002 dodge car van and my temp stays cold I've put coolent in it and it heated up a few minutes then on the way home it got cold again not understanding why
Milind N. Deuskar
Car petrol Indica zeta 2007 car runs for 30 km. Then temperature indicator zero or lowest. Giving me check engine & tripping car ac. Temperature indicator, sensors, cable fault possible problem
Devon Smith
1994 Chev S10 4.3L. Temp Guage doesn't move at all. Driove %0 mile round trip and guage didn't move at all.
Toy Corbett
I have an Audi A6T 2002 model. The low water warning is on and flashing on the led display and does not go off after topping up with water, also I noticed that the water temperature gauge is not moving from the bottom. It looks like there is a tiny bit of scum in the water reservoir; I don’t think its oil. Any ideas please.
kevin
Had both of my sensors replaced on my 2004 marquis and still cannot get the temperature gauge to work. Is there a sending unit for this car. I thought it could be the instrument cluster but I’m confused because everything else on the cluster works.
eric
Ok i have a 2014 nissan sentra am in the process of changing the oil or fluid from the transmission. My question is that do i have to remove just the overflow tube o do i have to remove the oil pan aswell? Also do i have to monitor the CVTF temperature?
Timothy samuel
I have issue on Toyota Corolla 05 temperature sensor which I have change temperature sensor and cluster still not working but I find out I that it work Rich the engine control box but the cluster not moving.what cause
MarkRager
I own a 2008 Chevy trailblazer Sometimes my thermostat Gauge works sometimes it does notBut it always blows hot airIt is never cold I had the Sensor replaced in it Still doing the same thing Could it be my thermostat
April
I have 2007 pontisc g6 2.4 temp gauge worked fibe then noticed it was stuck on lowest teading n the check engine light had came on took it auto parts place said was sensir or liw coolant or thetmostat well car heater is great and was on fill line in coolant as i left the parts store i noticed the needlecwas workibg again which it did for 2 days n onve again stuck on lowest reafinh just by touchibg sensor to assurecit was snug n placevit started working sgain so that mean the sendors not actually bad n could b lisecwire?
Cathy styles
My tempature gauge goes to right before the middle and doesn't say it's hot when it is hot. Because the coolant isn't wanting to flow through the engine??
Tina
Last spring I flushed the radiator on 1999 mazda b3000. This winter thermostat kept sticking so I had it replaced with new thermostat. Problem is.. The gauge stays on cold, truck got boiling hot on a short 2 mile drive. Waited for it to cool off then drove home with no problem at all. The guy said it could be air bubble or trash in the radiator. Gauge still stays on cold.
Rich
Hi my daughter has a Peugeot 207 1.4 petrol. It has had a new thermostat which then made the temp gauge work. Solved! A year or so later - stopped working again. I changed the coolant today got 4 litres out and put a new lot in 4L. (It’s idd that the system is supposed to hold 5.3L)!!! Anyway, there was no bubbling or rising liquid or anything , just gently filled it to minimum ran engine watched it drop kept filling until 4 L was put back and it was on maximum. Question is - why did it not need 5L and why does the gauge not work?
Collins Nweze
Thanks Magnus for the information. My Lexus 350 Rx 2008 model just had overheating problem without me noticing it on time. Reason was that the temperature guage was not working. It stays permanently at the safe zone, middle and I never suspected it was overheating until the cr stopped. When I checked the dashboard, the temperature guage was still at the middle and I continued my journey until the car stopped again. And I noticed that the engine was hot and the water in the radiator pouring out. My mechanic checked it and said the gasket has been damaged and is being replaced. Luckily for me, although the oil in the engine has not yet mixed with water, but it is blackish in colour. What steps should i take after the gasket fix? How do I know that the temperature guage is working to avoid being disappointed when it need it most?. Thanks, Collins, Lagos- Nigeria
Mario Martinez
Hello! Thanks for the information. I have a 2012 Ford E350, 5.4l v8 that has a temperature gauge that works intermittently. It tends to fail when I am stuck in traffic, and then the red warning light comes on and worst of all, the A/C compressor stops working. Sometimes, all I have to do is turn the engine off for a minute after getting out of traffic, and if I get going on normal traffic, everything works fine, gauge and A/C, but other times it will stay the same, and sometimes it will do it even if I am cruising along on the freeway. Any ideas? Btw, I am not a DYI person, I have two very good mechanics I trust, and they are both stumped.
Angel
I have a 2001 Ford e250 van with a 42 litre engine and my problem is my gauge stays on cold all the time I replaced my coolant temperature sensor and same problem then I put a jumper on the connector and the gauge went to hot and then I noticed that when I scanned my codes the temperature read 180 on the scanner so that led me to believe that my problem is some were between the computer and the gauge so now my question is how do I find out exactly were and how to find out
Heber slade
My 2015 acura tlx ...the engine temp gauge stays on cold for longer than normal...thank you