What does it mean?
This is a generic diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, Dodge, Jeep, Chevy, Ford, Land Rover, Toyota, Ram, etc. vehicles. Although generic, the specific repair steps may vary depending on the year, make, model, and powertrain configuration.
A stored P0622 code means that the Powertrain Control Module (PCM) has detected a malfunction with the generator field coil control circuit. The F simply reiterates that the field coil control circuit is at fault.
The field coil is probably most recognizable by its windings, which are visible through the ventilation holes of most alternators. The field coil surrounds the generator armature and remains stationary within the alternator housing.
The PCM monitors the continuity and voltage level of the generator field control circuit whenever the engine is running. The generator field coil is integral to the operation of the generator and maintaining the battery’s charge levels.
Whenever the ignition is turned on and the PCM is powered up, several controller self-tests are performed. In addition to running internal controller self-tests, the Controller Area Network (CAN) is used to compare signals from each individual module to ensure the various controllers interface correctly.
If a problem is detected in the monitoring of the generator field control circuit, a P0622 code will be stored and a Malfunction Indicator Lamp (MIL) may be illuminated. Depending on the perceived severity of the malfunction, multiple failure cycles may be required for the MIL to illuminate.
A typical alternator:
P0622 Alternator
How severe is this DTC?
Internal control module codes should be considered severe. A stored P0622 code could lead to various driving issues, including a no-start and/or dead battery condition.
What are some of the symptoms of the code?
Symptoms of a P0622 trouble code may include:
Engine driveability problems
Rough engine idle
Inadvertent engine stalling
Delayed engine starting
Other stored codes
What are some common causes of the code?
Causes
of this code may include:
Faulty PCM
PCM programming error
Open or shorted generator field control circuit
Faulty alternator/generator
What are the P0622 troubleshooting steps?
A diagnostic scanner, a battery/alternator tester, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information will be needed to diagnose a P0622 code.
Consult your vehicle information source for Technical Service Bulletins (TSBs) that match the stored code, the vehicle (year, make, model, and engine), and the presented symptoms. If you find the relevant TSB, it may provide helpful diagnostics.
Start by connecting the scanner to the vehicle’s diagnostic port and retrieving all stored codes and freeze frame data. You’ll want to note this information, just in case the code proves to be intermittent. After recording all relevant information, clear the codes and test-drive the vehicle until the code resets or the PCM enters readiness mode. If the PCM enters readiness mode, the code is intermittent and will be more difficult to diagnose. The condition that caused the P0622 to be stored may even need to worsen before a diagnosis can be made. If the code resets, continue with your diagnosis.
Use the battery/alternator tester to check the battery’s charge and ensure it is sufficiently charged. If not, charge the battery as recommended and test the alternator/generator. Follow the manufacturer’s recommended specifications for minimum and maximum voltage output requirements for the battery and alternator. If the alternator/generator is not charging, proceed to the next step of your diagnosis.
Use your vehicle information source to obtain connector face views, connector pinout diagrams, component locators, wiring schematics, and diagnostic flowcharts related to the code and the specific vehicle.
Check for battery voltage at the alternator/generator field control circuit using the appropriate wiring schematic and your DVOM. If not present, check the system fuses and relays and replace faulty components as needed. If voltage is found at the generator field coil control terminal, suspect a faulty alternator/generator.
If the alternator is charging and the P0622 continues to reset, use the DVOM to test the controller power fuses and relays. Replace any blown fuses as needed. Fuses should be tested under load.
If all fuses and relays appear to be functioning as expected, a visual inspection of the wiring and harnesses related to the controller is necessary. You will also want to check the chassis and engine ground connections. Use your vehicle information source to obtain ground locations for the related circuits. Use the DVOM to test ground integrity.
Visually inspect the system controllers for signs of water, heat, or collision damage. Any damaged controller, especially by water, should be considered faulty.
If the controller power and ground circuits are intact, suspect a faulty controller or a controller programming error. Replacing the controller will require reprogramming. In some cases, you can purchase pre-programmed controllers from aftermarket sources. Other vehicles/controllers will require on-board reprogramming that can only be performed by a dealer or other qualified source.
The field coil is an integral part of the alternator and generally cannot be replaced separately
Test the controller ground integrity by connecting the DVOM’s negative test lead to ground and the positive test lead to battery voltage