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Hey, Why Does My Car Smell Like Burning Plastic?

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Four common causes for a plastic burning smell from the vehicle and their related parts.
Another cause of a burning plastic smell could be any type of electrical system overload. Plastic coatings on wires can become heated beyond their limits. Burning can also occur when there is an electrical short circuit. Since most modern cars and trucks have a substantial amount of computer, electrical, or sensor wiring to ensure all essential control functions in your vehicle are working, it is vital to keep them running correctly. Be prepared to share with your trusted shop how they can best reproduce what you’re experiencing during their testing.

Common Causes For a Burning Plastic Smell?

The burning plastic smell is typically related to any electrical system overload. Plastic coatings on wires can become heated beyond their limits. Burning can also occur when there is an electrical short circuit.

  • Melted fuse box: The fuse box holds many fuses and connectors and has a vital role in the car's electrical system by protecting circuits and components. However, it can burn if there's an electrical overload or short circuit, producing a burning plastic smell.
  • Faulty blower motor: The blower motor is a mechanism that forces airflow in the vehicle and is essential for A/C and engine cooling. However, it can overheat due to internal electrical issues, causing a burning plastic smell.
  • Faulty alternator: The alternator is crucial to the electric system in a car; it's basically the powerhouse that generates and recharges the battery. Unfortunately, it can overheat and burn internal components, causing a burning plastic smell.
  • Road plastic on the exhaust: Road plastic like shopping bags or plastic debris can bounce on the exhaust and get stuck from the heat. In this case, the plastic keeps burning and producing a telling smell.
  • Relay failure: Relays are vital components in the electrical system; they transfer electricity from the control circuit to the main circuit, basically making a small switch activate a bigger car function(like turning a switch to activate the headlight). However, they can overheat due to exaggerated power drawing, causing a burning plastic smell.

A burning smell coming from the car is typically an early sign of damage. Unfortunately, turning a blind eye to the problem puts expensive wiring, harnesses, connectors, and computer controls at risk.

First, search under your vehicle for plastic bags stuck in the exhaust. In some cases, the plastic melts, and the burning smell travels through the heater and air-conditioning vents. If the problem persists, serious car problems might evolve.

Since most modern cars and trucks have a substantial amount of computer, electrical, or sensor wiring to ensure all essential control functions in your vehicle are working, it is vital to keep them running correctly. Be prepared to share with your trusted shop how they can best reproduce what you’re experiencing during their testing.

Let's Get To The Bottom Of It!

  • Q: Are you noticing problems with your car's stereo, lights, or starting process?

    Problems with your car's stereo, lights, or general accessories accompanied by a burning plastic smell can have to do with the alternator. The alternator is a component under the vehicle's hood that generates power for extra accessories, such as the radio, cabin lights, etc.

    However, alternators can develop issues and cause overheating. Commonly, damaged alternator terminals can melt and burn wire connectors, causing a burning plastic smell.

  • Q: Have you checked if there's something stuck under your car?

    Debris stuck in the car (like a plastic bag) starts melting as the engine heats, especially on long drives or while cruising a steep hill. Then, fans from the electric cooling and air conditioning condenser overheat because of built-up road debris, causing a high load or electrical short, which is a common problem.

  • Q: Are you noticing any electrical failure in your car?

    If, besides the burning plastic smell, you're noticing issues activating some of the car's systems, like internal lights, windows, and sunroof, the issue might be an electrical failure. Each of the car's systems runs on electricity and has plenty of wires and connectors that can burn and stop working. So, if you notice a specific system not working, it might be the culprit causing the smell.

    Plastic generally doesn't handle heat very well. Your car has many complex plastic-y electrical switches, like relays, which constantly transfer high loads. Unfortunately, this part can fail and cause burning plastic smells.

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Vehicle Health Inspection Proof

Explore the following typical inspection results that show a potential cause for the symptom and select the one you believe is similar to your vehicle's issue.

Plastic burning on the exhaust causing the burning plastic smell from the vehicle

Lifting the car and inspecting its underside is essential. The image above shows the exhaust pipe with plastic melt marks, possibly from road trash. The garbage was sticking to the hot exhaust, making the car immediately produce burning smells.

Splash shields are parts that prevent water and other objects from sticking under your car. In this case, the owner removed the plastic shield because it was damaged. Without replacing it, the car's underside became vulnerable to plastic bags, etc.

Does the issue look like this? if not accessible your shop will document it
A blower motor with wiring issues can melt connectors and malfunction

The mechanic spotted this failing blower motor while inspecting the car's cabin air filter. The blower motor works to provide airflow to the vehicle. The motor is part of the vehicle's electrical system and receives power current; if its resistors fail, it'll overheat.

It's common to associate the burnt plastic smell with oil-related issues, but that's not always the case.

The blower motor stays surrounded by plastic material, behind the vehicle's dashboard. Unfortunately, they might overheat when operating for a long time, burning surrounding plastic and causing a smell in the car.

This might occur more frequently in summer when drivers use the blower motor to escape the heat. So, replace cabin A/C filters regularly to avoid overload on this system.

Does the issue look like this? if not accessible your shop will document it
A blown fuse can melt nearby component like the fuse box cover, which is plastic, causing a burning plastic smell

This image shows melts on the fuse box and cover, resulting in a burning plastic smell. The cause was the charging system, which was overloading and overheating the wires and connectors.

The fuse box is a plastic container under the vehicle's hood that houses electrical fuses and relays; it is critical for the electrical system. The components inside the fuse box can overheat, short circuit, blow up, or even start a fire. In this example case, the extreme temperature, possibly due to a faulty resistor, melted parts of the fuse box.

In this case, the mechanic will test the charging system. Culprits can be a weak battery, faulty resistor, parasitic draws on taillights, or additional electric vehicle accessories.

Does the issue look like this? if not accessible your shop will document it
Car relay failure

The melting signs from the image are alarming; the mechanic saw them during an underhood inspection. The image shows the slot of relays under the vehicle's hood. This part of the electrical system usually sits adjacent to the fuse box, around the engine compartment.

Modern vehicles' relays constantly work to turn mechanical switches on and off; they are part of the electrical system and send power to different car components, depending on necessity. Unfortunately, these switches transfer high loads and can lose resistance over time, melting the connectors and wires and causing a burning smell.

Sometimes, relays just fail, but testing the system to learn if there is a complex reason is essential. In this case, the mechanic will do an extremely in-depth inspection.

Does the issue look like this? if not accessible your shop will document it
Alternator is overcharging and providing too much voltage due to a faulty voltage regulator, resulting in burned connections and burning plastic smells

In the example picture, the mechanic did an underhood inspection and saw the alternator terminal, which was melting and damaging the wire connector. The result was a burning smell.

The alternator is an under-the-hood part that generates electrical power to charge the battery; they are not bound to produce extreme temperatures and they have a voltage regulator to prevent that. However, alternators can fail, overheating and burning adjacent wires, plastic covers, insulation, and components.

In this case, the car was close to having critical failures. The alternator struggles to generate charge if the vehicle has various active electrical accessories. Therefore, modern vehicles commonly overwork alternators, connectors, and wires because of complex safety and convenience devices.

Does the issue look like this? if not accessible your shop will document it

Typical Makes

That need Burning Plastic Smell significantly more often than average vehicle makes

  • Make:

    Volkswagen

  • Model:

    Beetle, Jetta, Golf

  • Fuse Block Replacement

Is this the make you are driving?
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Typical Fixes to Address the Cause(s)

The following chapters bases themselves on experiences from our auto repair shop; we'll describe related problems' causes and fixes.

"Fuse Box Replacement" fixes "Melted Car Fuse Box and Cover"

Hey, Why Does My Car Smell Like Burning Plastic?
Sometimes a problem is more challenging to describe than it initially looked like. If you are not sure your problem is described by this article, please find below similar vehicle symptoms, which might describe better the issue you are experiencing.

Other things your auto repair shop might talk about:

Cooling system, Catalytic Converter failure, Engine oil overfilled, excess oil dripping, fuel lines, burning rubber, smell burning oil, oil leak, burning smell from car, burning oil smell, car engine. car smells. exhaust system. hot engine. brake pads. a few seconds.

Typical Fixes Pages: