LED Headlight Bulb Decoding Problem – Why And How To Fix?

Why do my LED headlight bulbs flicker and how to fix it? If you are going to replace your OEM car headlight bulbs with LEDs, Canbus Error Code is undoubtedly the most concerning to customers.

LED headlight bulb decoding problem is a distraction that basically reduces your ability to see better at night, so when your LED headlight bulbs start flickering, not working or causing dashboard warning, they need to be addressed promptly.

In this blog, you will learn what causes decoding problem of LED headlight bulbs and what you can do to fix it with these helpful tips.

What Are LED Headlight Decoding Problem?

If you experience the following situation after installing LED headlight bulbs when starting the engine, then you should have encounter a problem with the decoding of the headlights:

  • Dashboard Error Message
  • Radio Interference
  • Bulb Flash When Turned on
  • Bulbs Stay Illuminated After Turned Off
  • Daytime running lights are not working
  • Abnormally Dim Light Output

We’ve found that Volkswagen, Ford, Jeep/Chrysler, Mercedes, and vehicles using pulse width modulation (PWM) are most likely to cause decoding problems.

What Causes LED Headlight Bulb Error Codes?

Wrong Power Monitoring

In brief, the power of LED headlight bulbs do not match the current of OEM halogen lamps. For example,

the wattage of original halogen is usually 55W, and the working current is 4.5A. Some aftermarket LED car lights either have lower power raging from 20W to 25W or high power ratings from 60W to 110W.

As a result, some vehicles with strict calibration may be deemed abnormal, triggering error codes in the onboard computer system.

Headlight Circuit Problem

The error codes of LED headlight bulb may also be caused by a circuit problem. For example,Faulty components like the headlight switch or relay could also contribute. Advanced DIY enthusiasts with a voltmeter can diagnose by checking for voltage drop, a process detailed here.

In older vehicles, the headlight switch assembly contains a built-in circuit breaker. In case of a short circuit, both headlights may flicker together, but a single headlight flickering on and off independently suggests a different issue.

DRL Issues

Some vehicle manufacturers utilize Pulse Width Modulation (PW) for the daytime running lights. PWM effectively chops up the average power delivered, reducing it into discrete segments. If you were to replace an OEM halogen bulb with an LED headlight bulb on a vehicle that utilize PWM for the DRL, it will start to cause Canbus error code to due to the pulsating power.

However, if your DRL does not utilize PWM, then installing LED headlight bulb may result in flickering or failure to turn on because of the lower voltage of DRLs.


If you have just installed your LED headlight bulbs on your car and you go to turn them on to only see nothing, you may have a polarity issue. This is super easy to handle. Just take out the bulb, flip it and plug it back in.

How to Solve The Decoding Problem of LED Headlight Bulb?

Canbus Compatible LED Headlight Bulb

[NAOEVO NL Series LED headlight]

The most effective and direct way is to use NAOEVO’s Canbus Error Free LED Headlight bulbs, which come with additional Canbus drive to adjust their working current and bring them closer to the parameters that the Canbus system is looking for.

Besides, the Canbus driver will allow the electric system to ensure that the LED headlight receives a constant and steady supply of voltage. If your car is classic model or a German car, then such a LED headlight bulb is very necessary.

Load Resistor

Another valuable tool to address flickering is the load resistor, which ensures adequate current supply to the LEDs. Transitioning from halogen to LED headlights results in a noticeable decrease in power consumption.

You can regulate extra current using a load resistor, which allows your car’s computer system to communicate with the electrical system of LED headlights. Setting up load resistors is usually easy; you just plug them in and use them.

LED Decoder

An LED decoder is a helpful solution for fixing flickering LED lights. It stores and releases electric current steadily, which helps stabilize the lighting. Some car manufacturers use pulse power for halogen lights to reduce power usage and heat output.

This intermittent electricity doesn’t affect halogen bulb performance. However, when switching to LED headlights from halogen bulbs, you need a consistent current supply. That’s where an LED decoder comes in. It has high capacitance and ensures a steady flow of electricity.

Anti-flickering adaptor and warning cancelers

Flickering lights might occur when there’s a poor connection between your car’s electronics and the LED headlights. To fix this, you can use capacitors, warning canceler, or anti-flicker adaptor.

These devices act as intermediaries, enabling your car’s computer to communicate properly with the LED headlights. They’ll ensure that the flickering LEDs aren’t seen as a fault in your car’s electrical system. Also, check if the bulbs are securely installed in their sockets.

Another solution is to use an anti-flicker adaptor, a small device handy for various wiring issues. Installing it is straightforward: connect one end to the existing circuit and the other to the LED headlight. This is the simplest fix for flickering LED headlights. Just make sure to get the right adaptor for your LED headlight by matching their model numbers.

How Canbus Decoder/Resistor Work With LED Headlight Bulbs?

‘CANbus’ is an abbreviated form of ‘CAN bus’, which stands for Controller Area Network bus’.

In electrical terms, a “bus” acts as a central hub that facilitates communication between different circuits or components. A CANbus is connected to various parts of your vehicle and can detect faults in them. For example, low tire pressure might cause an error message to appear on the dashboard.

The principle is to increase the current in the car headlight bulb circuit. When a decoder is installed, the car’s onboard computer detects that the headlight current has returned to normal during self-check, preventing the malfunction indicator from lighting up. This is achieved through decoding.

Which Canbus Decoder Should I Need?

Now that we understand what a Canbus canceler/resistor is, the question remains: which shall I use? 

It usually depends on which bulb you’re buying.

If there’s a bulb fitting on the Canbus unit, then choose the corresponding fitting for your vehicle. For example, if you’ve got an H7 LED headlight bulb, we’d recommend that you purchase the H7 LED Headlight Canbus Adapter. Fittings such as PY21W, for example, would use a 21W CANbus adapter.

Similarly, if you’ve got a W5W, or another fitting that’s 5W, you’ll need a 5W CANbus. If you have a bulb such as a W16W and can’t find a unit to exactly match the wattage, choose one that’s closest but round up.

Best Canbus Error Free LED Headlight Bulb Recommend!

NAOEVO NL Series LED Headlight Bulb

If you don’t want to face the complex decoding problems caused by installing car LED lights, then we will highly recommend this NAOEVO NL series LED car headlights.

These LED headlight bulbs come with 6*70MIL flip chip so as to produce a high output of 180W 21600LM (Pack of Two). The 6500K cool white can significantly improve visibility and safety.

NAOEVO NL LED headlight bulbs are designed with external Canbus drivers which fit almost 99% of vehicles without error or flickering. A truly plug-n-play LED headlight bulb for your stock halogen bulbs.

NL LED car bulbs stand out because they have a built-in smart temperature control driver. This design protects the bulb from overheating, ensuring a less than 1% defective rate. NL LED headlight bulbs are available in H1, H3, H4(H/L), H7, H8/H9/H11, 5202, H10, H13(H/L), 9005, 9006, 9004(H/L), 9007(H/L), 9012, 880/881, D1/D3,D2/D4 ,H15. Choose the right bulb model for your car.


Now that you’ve understand the causes and solutions about LED headlight bulb decoding. As mentioned above, NAOEVO LED headlight offers solutions to decoding problems when installing LED headlight bulbs in your vehicle. By using Canbus-compatible LED bulbs or decoder, resistor kits, car owners can overcome these Canbus error codes and enjoy the benefits of LED headlight bulbs without any complications.

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