P0621Medium SeverityElectrical

Generator Lamp L Control Circuit Malfunction

What This Means

The generator lamp l control circuit malfunction has been detected. This relates to the charging system and alternator/generator control.

Common Symptoms

Check engine light on
Charging system warning
Battery light on
Reduced functionality

Common Causes

Faulty alternator
Wiring damage
Belt issue
Voltage regulator failure
PCM driver issue

Estimated Repair Cost

$100 – $700

Parts and labor (varies by vehicle and location)

Difficulty:Moderate

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For informational purposes only. Diagnostic trouble codes are starting points for diagnosis, not definitive answers. Always consult a certified mechanic for proper diagnosis and repair. Estimated costs vary by vehicle, location, and shop rates.