AutoCodes – Generic – P0622

P0622 Code - Generator F-Terminal Circuit

Quick Answer

The Engine Control Module (ECM) uses the Generator field duty cycle signal circuit, or F-terminal circuit, to monitor the duty cycle of the Generator. Common causes include Battery charge, Faulty Generator, Generator harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0622 indicates Generator F-Terminal Circuit.
Common causes: Common causes include Battery charge, Faulty Generator, Generator harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 80,479

How popular is this code, among other codes? Medium

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 15, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
Comments
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Code P0622 Description

The Engine Control Module (ECM) uses the Generator field duty cycle signal circuit, or F-terminal circuit, to monitor the duty cycle of the Generator. The Generator field duty cycle signal circuit connects to the high side of the field windings in the generator. A Pulse Width Modulated (PWM) high side driver in the voltage regulator turns the field windings ON and OFF. The ECM uses the PWM signal input to determine the generator load on the engine. This allows the ECM to adjust the idle speed to compensate for high electrical loads. The ECM monitors the status of the generator field duty cycle signal circuit. When the ignition is ON and the engine is OFF, the ECM should detect a duty cycle near 0%. When the engine is running, the duty cycle should be between 5 - 99%. The Diagnostic Trouble Code (DTC) will be set if the ignition is ON, and the engine OFF (Prior to Ignition ON, the ignition must have been OFF for at least 5 s), the ECM detects a PWM signal that is greater than 65% for 5 s.

OBDII Code P0622 - Generator F-Terminal Circuit - AutoCodes.com — P0622 Code - Generator F-Terminal Circuit

What does this mean?

What are the Possible Causes of the DTC P0622?

Battery charge
Faulty Generator
Generator harness is open or shorted
Generator circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0622?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

If the battery is OK, then the alternator is more than likely the problem.

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0622 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Information for Specific Makes

P0622 Buick — Generator F-Terminal Circuit
P0622 Cadillac — Generator F-Terminal Circuit
P0622 Chevrolet — Generator F-Terminal Circuit
P0622 Chrysler — Generator Field Not Switching
P0622 Dodge — Generator Field Not Switching
P0622 Ford — Generator Field Terminal Circuit
P0622 GMC — Generator F-Terminal Circuit
P0622 Isuzu — Generator Field Control Circuit Malfunction
P0622 Mazda — Generator Malfunction Load Input Out of Calibration
P0622 Mercedes-Benz — Generator Field 'F' Control Circuit Malfunction
P0622 Mitsubishi — Generator FR Terminal Circuit Malfunction
P0622 Pontiac — Generator F-Terminal Circuit
P0622 Saturn — Generator F-Terminal Circuit
P0622 Suzuki — Generator Field Control Circuit Malfunction

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0622 Code

No Frequently Asked Questions about P0622 Code found.

Discuss the causes and fixes for P0622 OBDII Code

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tano
Date: August 3, 2016 at 6:21 pm

I change 3 times the alternator..and check the volts in the plug and all is right..but the light is on...

Reply to Comment
OBDIITech
Date: August 3, 2016 at 6:22 pm

What model and year is your vehicle?

Reply to Comment
Khalid Ali Mohammed
Date: January 18, 2017 at 5:24 pm

My car is toyota hilux d4d 2007 model it has p0622 problem i changed the alternator butthe check engine light wouldn't be off. What should I do? Any help tanx

Reply to Comment
Eugen MARES
Date: February 20, 2017 at 11:26 pm

Hello. I also have a Toyota Hilux 2.5L diesel D4D, 88kw, manufacturing year 08.2008. Three or 4 years ago i experienced the first time check engine with OBD II erorr code P0622. After a few km, the check engine mark dissapear. Few days ago, the erorr apears again. Is interesting that all the engine parameters was ok, the baterry ok, the alternator ok (double checked with Texa dedicated tester for toyota hilux). I observe that both the 1st and 2nd time, the outside umidity was around 85% and the outside temperature around 6-8 celsius. I proceed to erase the erorr with my OBD II mobile application and everything remain (untill now) ok. No erorr. Nobody does't realize what was wrong.

Reply to Comment
Eugen MARES
Date: February 20, 2017 at 11:31 pm

Completion: as a direct action, i remove the air filter housing, pull out the electrical socket from the alternator, clean the contacts with contact cleaner spray. After that everythig is ok.

Reply to Comment
OBDIITech
Date: February 21, 2017 at 12:20 am

Thank you for the information!!

Reply to Comment
Troy clements
Date: April 6, 2019 at 9:25 pm

Hi I have a 2007 prado and I have no air con, no indicators,and the auto won't engage until I use the unlock button after a while the check engine light came on so I checked the code and got code p0622.
What could be wrong, and how to fix.
Thanks
.

Reply to Comment
Caz
Date: March 12, 2021 at 5:05 am

Had the same issue with the engine light. Used a cheap diagnostic tool that came up with PO622. Used sensor cleaner and sprayed the air filter sensor and pulled out all visible others and cleaned them thoroughly. Turned the 2008 D4D 3Litre Hilux back on after giving some time for the sensor cleaner to evaporate and all its good. Quite a bit of dust around those 3 wire harnesses going into the computer module in the engine bay firewall on the right hand side in Australia. These are possibly on the left in left hand drive vehicles.

Reply to Comment
Caz
Date: March 12, 2021 at 5:13 am

So thanks to other comments and those on other sites as they suggested the filter sensor as a first point to clean. Note 1: I forgot to simply clean this sensor alone and cleaned all of them before turning the engine back on. Note 2 : I've only driven a short distance since the light went off so will post back if this is not a solution as written below in my other post.

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OBDIITech
Date: March 12, 2021 at 1:16 pm

Thank you for sharing!!

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