Why does Honda Civic heater only work while driving?

The Honda Civic is produced by the Honda Motor Company. They are fast compact cars and have an excellent power-to-weight ratio, amazing drivetrain gearing, and shift patterns.

The Honda Civic is a wonderful car that requires cheap maintenance. Although the Honda Civic does not suffer from the ball joint pulling issue, owners usually complain about the heater.

This piece will delve deeper into the subject: why does Honda Civic heater only work while driving?

A faulty heater is one of the most common Honda Civic car problems. When your heater only works while you’re driving your car, it’s a bit unsettling.

This problem can be caused by a defective heater valve, a radiator leak, or a blocked heater core, among other things. In this article, you’ll learn about the causes and perhaps how to solve them.

Some Honda Civic owners complain that their heater only works when the engine is revved or while the car is moving. This is a bothersome problem, especially in the cold.

To figure out what’s causing this, you’ll need a solid grasp of how your car’s heating system works. Dive in to see how to identify the issue (s) and how to resolve them.


How to detect heater issue and correct them

The first step is to identify where the problem is coming from. The source of the problem, as with any other technical problem, could be anywhere.Why does Honda Civic heater only work while driving?

Coolant levels and a potential coolant leak are the most likely culprits. The heater control valve, as well as the vacuum hoses linked to it, should be checked after too.

Why does Honda Civic heater only work while driving?

When your Honda Civic heater only works while driving, there are probable causes for that. Engine coolant, heater control valve, vacuum hoses, and the thermostat are among the most common causes. This particular heating issue can be caused by any of these problems.

Heat will constantly be generated while driving since the coolant will gradually get hotter, causing the heater to produce hot air from the engine core.

If all other factors appear to be in order, you get to the thermostat, which should be the source of the problem based on the process of dismissal. If you’ve checked everything up to the thermostat and still haven’t found the problem, it could be any of the following problems listed below.

  • Engine coolant

Assuming your engine coolant is the source of the problem, it’ll either be too low or too high. If your coolant levels have dropped, it’s possible that there’s a leak somewhere in the system.

You can fix the coolant by flushing it to remove any impurities. If all of the system’s components are in good working order, you may just need to clean the coolant and replace it with fresh, pre-diluted. But a damaged coolant should be replaced and not repaired.

  • Low coolant

The heater in your car works by diverting part of the heated coolant to the heating core. The heated air formed by the heating core is then blown into your vehicle by a fan. So, if the coolant level is low, there may not be enough to divert into the heating core.

If you hear unusual sloshing or notice that your engine is running hotter than usual while driving, you may have a coolant problem. You can also just check the coolant level in your vehicle. It shouldn’t be completely empty in a short amount of time.

The most straightforward explanation is that your coolant level is low. In such a scenario, all you have to do now is top it off. However, if you’re losing a lot of coolant, you’ve probably had a leak.

  • How frequently should you flush your coolant?

The general consensus is that it should be done every 100,000 miles. However, if you’re having problems with your heater, this could change.

  • Heater control valve issue

The heater control valve is a cooling, heating, ventilation, and air conditioning (HVAC) system component. It controls the flow of coolant from the engine to the heater core, which is housed inside the car.

The heater control valve is designed to open when your engine reaches its optimal operating temperature. If it fails to do so, the car may idle without producing any heat.

The rate at which coolant flows through the heater core is controlled by the heater control valve. On the heater inlet hose, there is a valve. A malfunctioning heating valve is the next likely cause of the problem.

The heater valve functions in the same way as a thermostat, only it permits coolant to enter the heating core rather than the radiator. To diagnose if the problem is the heater control valve, allow your vehicle to run for at least 15 minutes with the heater on. The heating valve will then be found.

It’s often found behind the engine on the firewall. Touch the hoses on both sides of the valve with caution. The heater valve is defective if the engine side hose is hot and the heater side hose is cool.

Leaks in the vacuum hoses that connect to the heating control valve can cause it to fail to open. If these hoses are leaking, you’ll almost certainly smell coolant under the hood.

Even if this isn’t the main reason your heater isn’t operating properly, you’ll need to fix them if they come out to be leaking.

Take your car to a mechanic to determine whether your heater valve is cable, vacuum, or electronically driven before attempting to repair it.

  • Thermostat

The thermostat functions similarly to a control valve, opening and closing in response to temperature. The thermostat separates the engine from the radiator until a particular minimum temperature is reached.

The engine would always lose heat to the radiator without a thermostat, making it take longer to respond. A faulty thermostat may also be the source of the issue.

If the thermostat fails to close, which can happen when the coolant temperature is too low, the engine will take a long time to warm up.

To solve the problem, you’ll have to replace the thermostat that’s been pulled off. Make sure your vehicle is completely cool before you begin. Then, at the base of the radiator, look for the thermostat.

By first placing the radiator hose in a bowl and then removing it, you may easily remove it. In order to replace the faulty thermostat, you must first remove it. Replace the pipe and top off the coolant if necessary.

  • How can I tell if the thermostat in my car is working?

There is a straightforward way to tell that your car’s thermostat is working. Start your car and drive it for around 15 minutes to see if this is the issue.

Then switch it off and thoroughly inspect the radiator hoses. One of the hoses should be hot, while the other should be cold. If both hoses are heated, your thermostat is stuck open.

  • Blown Head Gasket

The internal combustion process is sealed by the head gasket, which also prevents coolant and oil from mixing as they move from the engine block to the cylinder head.

A blown head gasket is another reason why your heater only works while driving. If you opened up the radiator cap and looked inside, you would notice something like exhaust fumes.

Some common symptoms of a blown head gasket are that the exhaust emits a cloud of white smoke, and there are no leaks but unusual coolant loss.

You can see the fumes in the radiator if you shine a flash light over it, but you can also double-check by squeezing the upper radiator pipe. If there is exhaust in there and you squeeze it, it will come out.

  • Radiator leak

Many of the heater problems listed already can be caused by a leak in some area of your radiator. Your car is losing coolant if there is a leak someplace.

And this can result in heater troubles such as air obstruction and other undesirable consequences of low coolant. By simply looking, you should be able to locate the leak quite quickly. Check for coolant leaks near the radiator, particularly where the hoses attach.

The solution to this problem is contingent on the source of the leak. If your radiator has a crack or other source of damage, it will almost certainly need to be repaired or replaced.

If the leak is coming from the hose’s end, though, it’s a straightforward remedy. Simply tighten the clamp that holds the hose in place, and the problem should be resolved.

  • Heater core is blocked

Because of its tiny size, the heater core is usually hidden under your dashboard and can cause problems. It’s easy for the little openings within to become clogged.

Old coolant, as well as dirt and other tiny debris, are the most common causes of blockages. Once you clean it, the heater might start working well.

  • What is the best way to test a heater core?

Allow your car to idle for 10 minutes with the heater on to check whether this is the problem. After that, double-check the hoses.

The heater core hoses are located behind the engine on the firewall. If they aren’t both heated, you’re most likely dealing with a blockage.

  • What is the most effective way to clean a heater core?

The simplest method for cleaning a heater core clog is to use a flushing chemical. These cleaners are engineered to safely infiltrate your cooling system and remove any obstructions.

  • How much does it cost to replace a heater core?

It can cost anything from $500 to $1,000 to replace your heater core. You’ll only have to pay for the replacement parts if you do it yourself.

If you hire an expert to fix it, it will not cost more than $800 to $1,200. However, prices will vary depending on your location.

Does my car’s heater have a fuse?

Yes! Your car’s heater has a fuse. A fuse problem, on the other hand, is doubtful to be the reason for the heater only working when the car is in motion.

This is due to the fact that it regulates the flow of electricity to your heating system. As a result, if the fuse blows, your heater will be rendered useless.

By searching inside your fuse box, you can see if the heater fuse is blown. To locate your fuse box and determine which fuse controls the heater, check your car’s owner’s manual.

Which Honda Civic years are more affected with the heater issue?

The heater issue is not prevalent in some Honda Civic models. However, the model years from 2006 to 2016 appear to be the most plagued by this type of heater issue.

This isn’t to suggest that this problem won’t impact other Civics, but it seems to be a widespread issue for these model years in particular.

Does the weather have a role in the Honda Civic heater issue?

Yes! You will find this very common during the winter. Vehicle fluids, particularly coolant, can thicken in cold weather. The thicker your fluids are, from engine oil to coolant, the more difficult it is for them to travel smoothly where they are needed.

If you have the same heater problem when idling, it will be significantly more difficult for those fluids to warm up as they should be unless you start driving at a high pace.


Finding the exact reason why your Honda Civic heater only works while driving might be difficult to figure out. Because your heater problem could be caused by a variety of factors, it’s important to understand what they are and how to recognize them.

However, you should start by looking for air in the system. It’s possible that the system has trapped air. Running a proper diagnosis is the best way to go about it. Take your car to a mechanic for this. You can do it yourself once you’ve figured out what the problem is.

Leave a Comment

Your email address will not be published. Required fields are marked *