We know our four-wheeled buddy can produce a symphony of sounds, right? For instance, the purr from engine, humming rhythm from tires, and sporadic noises are very common to hear. But when the car suddenly starts wailing like a police siren on a hot pursuit – it will make a question come out – “Why is my car making a siren noise?”
Your car’s siren noise may be a translation of something messed up under the hood. Well, siren noise can be a sign of a failing turbo, a large vacuum or exhaust leak, or a damaged intake (1). It may also happen due to worn-out bearings in the engine (2).
For a squealing sound, consider there is a problem with the serpentine belt. Other reasons for siren noise include worn-out gears, low transmission fluid levels and damaged idler pulley. However, I welcome you to go through this blog to know the reasons elaboratively. And I assume you have 2-3 minutes to read this thoroughly.
Car Siren Noise – Why Is It Different from Other Sounds of a Car?
Of course, each vehicle has its style of creating noise. In other words, a car can produce different types of sounds (3,4,5,6,7)
| Noise Type | Indication |
| Screeching | Worn brake pads |
| Knocking | Wrong type of gasoline |
| Clicking | Failing CV joints |
| Rattling | Loose lug nut, issues with exhaust system |
| Whining or growling | Low power steering fluid level |
| Ticking | Injectors |
Thus, I am here just to talk about siren noise. So, let’s focus on it.
For sure, a car siren noise is often related to emergency vehicles. They can be police cars, fire trucks, and ambulances. When you hear it from a personal vehicle, it can cause concern. After all, it is not typical for your car.
This noise may feel like a prolonged “Waaaaaahhhhhhh”, a loud and high-pitched sound. It differs from other common car noises as I mentioned in the above table. However, it may occur at any time. But you may hear it mostly when the car is in its motion. Its frequency can change or increase with the car speed.
Should you worry about the siren noise from your car? You know, it does not directly affect the car engine performance. Usually, the noise level of a vehicle is 70 dBA. It can increase to 115 dBA for an ambulance siren. Hence, it is related to the sound produced by the siren, not the car’s engine (8).
What are the Causes of Car Siren Noise?
That’s why you are here to know, isn’t it? Don’t worry. In this part, I will describe all possible reasons to car siren noise – in detail.
Faulty Serpentine Belt
The most common reason for a car siren noise is a defective serpentine belt (also known as a drive belt). When it gets worn out or damaged, it can cause a noise like siren. If it’s the reason, you may possibly hear a screeching sound from the engine bay (9). Besides, you may get warning lights on the dashboard when you hear this noise.
Power Steering Pump Malfunction
A power steering pump helps you to steer your car easier. But it may produce moaning, whining, or siren-like noise when it fails or gets damaged. You will usually hear a siren when you turn the vehicle. Usually, a leak in the pump or low fluid level causes issues like the siren noise and difficulty in turning the wheel (10).
Alternator Defects
The alternator charges your vehicle’s battery. Also, it powers the electrical system when the engine is running. But its defects can cause a siren-like noise in cars. But how? When your car has worn alternator bearings or a loose or worn alternator belt, it will cause a siren noise (11). Sometimes, you may hear squeaking, squealing, or grinding noises, too (12).
Turbocharger Complications
If you hear sirens from your turbocharged car, it asks you to focus on it. Typically, this noise is caused by a damaged compressor wheel or failing blades within the turbo (13). It may gradually get louder. Besides, it may refer to poor acceleration and a significant drop in power (14).
Some other symptoms of a failing turbo besides siren noise are blue/grey exhaust smoke, a blocked diesel particulate filter, and increased back pressure.
Brake System Woes
Problems in brake systems like worn down disc pads, damaged or low-quality pads, and warped or severely worn brake rotors cause siren-like noise (15,16). When these problems appear, you can hear metallic, screeching, squealing, or squeaking sounds.
Additionally, dust and accumulated debris can cause squealing noises. Even you may hear thumping noises from the front brakes, which indicates rotor damage or rust.
Alarm System Activation
In a car alarm system, you can find a series of sensors connected to a central unit. This unit activates alarm devices like the car’s horn, headlights, or an installed siren when the sensors detect certain activities (17, 18). However, when these sensors malfunction, you may still hear the siren noise.
Exhaust System Leaks
If you find a siren-like noise from the exhaust system, it may indicate several things. For example, you may get a whirling sound that changes pitch or volume based on the engine speed. It may happen due to belt-driven accessories or the actual belt.
If you get a siren noise with a loud metallic vibration, something is touching the exhaust pipe. Also, it may indicate a clamp, support bracket, or mounting is loose (19). Furthermore, if any of the exhaust pipes or tubes break or crack, they can cause an exhaust leak. And this leak will make the engine excessively noisy (20).
Vacuum Leaks
A leak in the vacuum can also be the cause of unbearable ambulance-like siren. Particularly consider it as the reason if the whistling sound becomes more noticeable when you accelerate (21).
Wheel Bearing Wear
Symptoms of worn wheel bearings in cars include snapping, popping, or clicking (a kind of siren-like noise). It indicates that the outer CV joint of the wheel is damaged or worn out (22). You may also hear a loud grinding or roaring sound from the tire area of the car. However, the noise may get louder as the vehicle accelerates.
Diagnosing Car Noises: Tools and Techniques
You can use several methods and tools to diagnose the siren noise in your car. I suggest you start with a visual inspection (besides using ears and hands). Yes, it’s time to listen and eye on the spots. Look for noticeable signs of damage or wear, like a frayed serpentine belt or leaking fluids. Then again, inspect power steering pump, timing belt, fuel pump, or alternator bearings.
Now, locate the sound source. In this case, you may use specialized tools. I am suggesting you Steelman products (23,24). These tools can detect the source of squeaks, rattles, and other unusual noises throughout a car’s chassis. More precisely, these tools are available as a set of stethoscopes, a multimeter, and a code reader.
If you don’t have tools like I suggested, you can take a long screwdriver. Then, place one end of the screwdriver on your ear. Then, bring the other end near the pulley or other potential sources of siren noise.
You may also use apps like My Car Makes Noise and ClingClanger. These apps work like magic! Trust me; they help diagnose car noises by providing a sound library for comparison or analyzing the sound directly (25).
Call a professional mechanic if you cannot handle the job. I guess that will save you time and obviously your car.
Conclusion: Solutions & Prevention to Car Siren Noise
Why is my car making a siren noise? Till now, I have explained the reasons and ways to diagnose siren-like noise in your vehicle. I will conclude the discussion with solutions and prevention to this problem.
Replace the defective components in your vehicle if they are causing the sound. For example, you can repair or change the serpentine belt, power steering pump, alternator, turbo, and wheel bearings.
If you want your car out of unnecessary siren noise, you can prevent it by regular maintenance. Change car oil, rotate the tire, and lube the engine and other components properly to avoid listening to siren noise.
You may need to spend an average of $50-$200 for a professional car diagnosis. It may not be necessary if you prevent the issue before.
Thanks for reading this blog. Have a nice day!
