U1521
Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus
U1521 is an OBD-II diagnostic trouble code meaning: Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus. Common causes: broken or damaged lin bus wires, malfunction of the headlight control module. Estimated repair cost: $56–167.
Symptoms
- Incorrect operation of the left headlight
- No response to headlight leveling
- Dashboard warning
- Headlights work in emergency mode
Causes
- Broken or damaged LIN bus wires
- Malfunction of the headlight control module
- Problems with power or grounding of the headlight
- Malfunction of the leftmost headlight
- Corrosion of contacts in connectors
How to Fix
- Check the integrity of the LIN bus wires
- Inspect connectors for corrosion or damage
- Check the power supply and grounding of the headlight
- Test the headlight control module
- Replace the faulty headlight if necessary
Related codes
FAQ
What does the U1521 code mean?
U1521 is an OBD-II diagnostic trouble code that indicates: Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus
What causes a U1521 error code?
The most common causes of U1521 include: Broken or damaged LIN bus wires; Malfunction of the headlight control module; Problems with power or grounding of the headlight; Malfunction of the leftmost headlight.
How do I fix a U1521 diagnostic trouble code?
To fix U1521: Check the integrity of the LIN bus wires. Inspect connectors for corrosion or damage. Check the power supply and grounding of the headlight. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U1521?
Limited driving only, diagnose soon
How much does it cost to fix U1521?
The estimated repair cost for U1521 is $56–167. Actual cost depends on your vehicle, location, and labor rates.
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