Alternator (generator) control

What it means

On many cars the engine computer controls how hard the alternator charges. These codes mean the control or feedback line between the computer and the alternator is faulty.

Codes in this group

Bank 1 is the side of the engine that has cylinder 1. Sensor 1 is before the catalytic converter and sensor 2 is after it. More terms explained.

What you may notice

• Battery warning light
• Battery going flat
• Lights dimming

Common causes

Most likely first:

• A failing alternator
• A corroded or loose plug on the alternator
• Broken wiring between alternator and computer
• A worn drive belt

What to check first

• Check the belt that drives the alternator is present and tight
• With the warning light on, the car runs on the battery alone and will stop when it is drained: head for a workshop, with lights and air conditioning off if safe

Have a mechanic confirm. A fault code tells you which system reported a problem, not which part has failed. The same code can have several causes, and they differ between car models. Use this page to understand the code, then have a qualified mechanic test the car before any part is replaced.

After the repair

Once the cause is fixed, the code can be cleared with a scan tool, or the warning light goes out by itself after several trips without the fault. Clearing a code without fixing the cause only hides it for a while. More about clearing codes.

Related codes

Engine overheating or overspeed (P0217), Fuel level sensor (P0460), Radiator cooling fan circuit (P0480), Vehicle speed sensor (P0500), Idle speed control (P0505), Brake pedal switch (P0504), Engine oil pressure sensor (P0520), Air conditioning pressure sensor (P0530). All codes.

Written in November 2026. These are generic OBD-II codes, the same on all makes. Causes and repair steps differ between models.