B3420

Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$56–167 (est.)

Symptoms

Incorrect headlight angle
Error message on the dashboard
Flashing headlights

Causes

Malfunction of the level sensor on the rear axle
Open or shorted wiring harness
Problems with the headlight level control module
Contact corrosion

How to Fix

Check the level sensor on the rear axle for damage
Check the integrity of the wiring harness and contacts
Scan the control module for errors
Replace sensor or wiring harness if necessary

Related codes

B3421 B3422 U0121