P0620

Symptoms

• The Check Engine light comes on
• The battery indicator on the dashboard is on
• Unstable on-board voltage
• Accelerated battery drain
• Lighting flickering when load changes

Causes

• Open or short circuit in the generator control circuit (L-wire/D+)
• Faulty generator voltage regulator
• Alternator brush malfunction
• Open circuit in the generator excitation circuit
• ECU malfunction (generator control channel)

How to Fix

1. Measure the voltage of the on-board network with the engine running (normal 13.8–14.4 V)
2. Check the generator control wire between the ECU and the L/D+ terminal
3. Check generator output voltage and current under load
4. Check the brushes and slip rings of the generator
5. Check the voltage regulator - replace if necessary
6. If the wiring and generator are working properly - ECU diagnostics

Related codes

Error P0620 by Vehicle Brand