Solving Decoding Problems in LED Headlights: Causes and Professional Solutions

Today we are talking about the decoding problems encountered during the use of LED headlights.

Ⅰ. Why Do Decoding Problems Occur? 

Modern vehicles use CANbus to monitor and control components like headlights. The system transmits information between the car computer and parts. It detects issues with lights via pulse signals and current changes. If a problem is detected, the dashboard shows an alarm. LED devices can block pulse signals, causing lights to flash.

Here's the catch:

Current sensitivity: LED bulbs consume ~30-200W, which is different from the 55W fixed by halogen bulbs. The can bus detects this weakened or enhanced current as a "fault" and triggers a dashboard error.

Pulse signal interference: The LED driver may block or distort the can bus diagnostic pulse, causing flashing or random shutdown.

Resistance mismatch: Without proper load simulation, the vehicle's computer mistakes the LED circuit for damage.

If you have the following typical symptoms after installing LED headlights, then you should have experienced the problem of headlight decoding:

1️⃣ Dashboard error messages
2️⃣ Headlight flickering
3️⃣ Daytime running lights failure
4️⃣ Random light shutdowns

Ⅱ. How do we solve the problem of car light decoding?

Professional Solutions: From Resistors to Super Decoders

The solution is to add a resistor kit, capacitor or resistor plus capacitor device to the lamp circuit to increase the load current of the lamp to and close to the level of the halogen lamp (55W), and use the capacitor to solve the can bus pulse problem. Specifically, we have three solutions for different types of LED headlights and different cars.

1️⃣ ​Resistor Kit

• ​Principle: Increase circuit load to simulate halogen lamp power（~55W)
• Installation: Parallel resistor to LED circuit, need to be fixed on metal parts (to avoid plastic parts heat deformation).
• Drawback: The resistance heat is large (working temperature ≈150°C), may reduce the LED life.
• Best For: Low power led bulbs (≤30W) or cost-sensitive modifications.

2️⃣ ​Capacitor

• Store electrical energy and release smooth current to eliminate flicker caused by CANbus pulse interference.
• Advantage: The heat output is much lower than the resistance, suitable for high power leds (45W-85W).
• Technical Limitation: The voltage matching problem of all models cannot be solved, and most of them need to be used with resistors.

3️⃣ ​Super Decoder

• Principle: Integrated resistance + capacitor + voltage regulator module, intelligent regulation of current/voltage.
• Performance: Solve complex CANbus protocol compatibility issues (such as Jeep, BMW and other brands).
• Cost: Higher price, but the best stability
  

Tip: Not all cars will have decoding problems with LED bulbs, and NOVSIGHT's LED headlight bulbs have a built-in decoding chip that can solve more than 90% of decoding problems. Only Volkswagen, Dodge, Jeep, BMW, Volvo and a few other brands of cars, prone to decoding problems, this time you can use external decoders to solve.

Buy NOVSIGHT Super decoder: Click here

Decoder installation tutorial: Click here

Novsight Automotive Lighting has always been working hard to create a safe and convenient car life for customers. Any Novsight customer who encounters flickering or error messages can click here to contact our customer service in time, and we will do our best to solve your problem.