Fault code P0622 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0622 – Generator Field "F" Control Circuit Malfunction

P0622: Causes, signs and repairs

Error code P0622 is displayed and the check engine light is on - what does this mean?

The DTC P0622 is recognized by the OBD system when there is a problem with the alternator field control circuit. This fault code relates to the vehicle's charging system and can occur with different manufacturers, although the specific definition may vary slightly.

What can cause this fault code?

Defective alternator/alternator
Damaged cable connections to the alternator
Loose or corroded plug connections
Defective alternator field control module
Blown fuse in the charging system
Worn carbon brushes in the alternator
Defective voltage regulator
Short circuit in the generator field circuit
Poor earth connection on the alternator

What symptoms occur in parallel with fault code P0622?

Battery warning light: The battery light in the dashboard lights up
Weak battery: The vehicle battery discharges quickly
Starting problems: The vehicle is difficult or impossible to start
Weak lighting: Headlights and interior lighting are dimmed
Electrical problems: Various electrical systems are not working properly
Engine stuttering: The engine runs unevenly at low engine speeds

How to fix the problem of error code P0622?

Repairing the P0622 trouble code requires a systematic diagnosis of the charging system.
Checking and replacing the defective alternator if the charging output is below specifications
Repair or replace damaged cables between the alternator and control unit and check all connections
Cleaning and fixing all plug connections on the alternator and replacing corroded connections
Replacing the generator field control module after checking the electrical signals
Checking and replacing blown fuses in the charging system and rectifying the cause
Replacement of the carbon brushes in the alternator or complete alternator repair
Installation of a new voltage regulator after measuring the output voltage
Repair of short circuits in the wiring through insulation or cable replacement

FAQ - Frequently asked questions about DTC P0622

Can I continue driving with error code P0622?

Continuing to drive with the code P0622 is only recommended for short distances, as the battery will not be charged properly and the vehicle may come to a standstill.

How much does it cost to repair fault code P0622?

The repair costs for P0622 vary between 150-800 euros, depending on whether only cables need to be repaired or the entire alternator needs to be replaced.

How do I recognize a defective alternator with P0622?

A defective alternator is indicated by a charging voltage below 13.5 volts when the engine is running, unusual noises or a permanently illuminated battery light.

Can I repair fault code P0622 myself?

Simple repairs such as cleaning connections are possible, but replacing the alternator or voltage regulator requires specialist knowledge and the appropriate tools.

How long does it take to diagnose P0622?

The complete diagnosis of EOBD error code P0622 takes around 1-2 hours in the workshop, as the entire charging system has to be checked.

Does fault code P0622 occur more frequently in certain weather conditions?

Yes, fault code P0622 can occur more frequently in extreme cold or heat, as these conditions put a strain on the electrical components of the charging system.

Vehicles in which fault code P0622 occurs most frequently

Fault code P0622 is a generic OBD code that indicates problems with the alternator field control and can occur in various vehicle manufacturers, but is most common in the following vehicles:

Ford: Focus, Fiesta, Mondeo, Transit (2008-2018)
Chevrolet: Cruze, Malibu, Equinox, Silverado (2010-2019)
GMC: Sierra, Terrain, Acadia, Yukon (2009-2017)
Cadillac: CTS, SRX, Escalade, ATS (2008-2016)
Buick: LaCrosse, Enclave, Regal, Verano (2010-2018)
Opel: Astra, Insignia, Corsa, Zafira (2009-2017)
Pontiac: G6, G8, Solstice, Vibe (2008-2010)
Saturn: Aura, Vue, Outlook, Sky (2007-2010)

If code P0622 occurs in your vehicle, you should first have the battery voltage and alternator charge output checked. Early diagnosis can prevent expensive consequential damage to the battery or other electrical components. If problems persist, it is advisable to visit a qualified workshop, as the charging system is a safety-relevant system.

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