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P0622 OBD-II Trouble Code: Generator Field "F" Control Circuit Malfunction

Check Engine Light

P0622 code definition

This code is defined as the generator field “F” control circuit malfunctioning.

What the P0622 code means

When the PCM (powertrain control module) logs a P0622 trouble code, it’s because it’s detected a problem with the generator field control circuit. The PCM uses the generator turn-on signal circuit to manage the generator. When it wants to take control, it sends a five-volt signal to the voltage regulator through the generator turn-on signal circuit.

This forces the voltage regulator to start controlling the generator field circuit. Once the PCM enables the generator, the voltage regulator independently controls the generator. However, during this process, if it notices something is wrong with the generator field circuit, this trouble code is stored.

Depending on the exact problem, it could be reported by the body control module, the antilock brake control module, the alternative fuel control module, the anti-theft module, the turbo control module, the instrument panel control module, the climate control module, the cruise control module, the traction control module, the proximity alert module, and the fuel injection control module. Others could report the problem too. The reason this is important is because it could take several incidents before the Check Engine light comes on. It all depends on the module that reports the issue to the PCM first.

What causes the P0622 code?

One simple reason for the code could be a battery charge issue. Otherwise, these three causes are the most common:

  • A malfunctioning generator
  • A generator harness that is shorted or open
  • A generator circuit that is suffering from a faulty electrical connection

The least likely reason would be that the PCM simply stored the code erroneously, but it is possible.

What are the symptoms of the P0622 code?

As we mentioned above, the Check Engine light should come on, but it might take more than one incident before this happens. In that case, a scan of the vehicle may show that the P0622 code is pending. Other symptoms are more serious. The battery could discharge, for one thing. Acceleration might become difficult. Fuel efficiency will probably suffer too.

When driving, you might find that shifting is a challenge. The engine may also stall out or even start vibrating. If you put it in idle, the engine may make a weird noise.

How does a mechanic diagnose the P0622 code?

A qualified technician will begin their diagnosis by using an OBD-II scanner to find which codes have been logged by the PCM. After that, they’ll probably examine the wires and connectors before moving on and doing the same to the control modules.

The Control Area Network (CAN) will most likely need to be inspected as well, which could mean taking out every pin in the process. This would require the use of a diagnostic CAN scanner and memory-saving tool.

Common mistakes when diagnosing the P0622 code

A lot of underlying issues could be playing a role in this code being stored. This is why the mechanic must take each code one at a time and fix them in this order by using the freeze frame feature of their OBD-II scanner.

How serious is the P0622 code?

The problem is fairly serious when you consider its impact on drivability. It could really cripple a car’s capabilities. That being said, the problem with the CAN could mean something more widespread is happening with the vehicle’s electrical functions which might represent a larger issue.

What repairs can fix the P0622 code?

There are a few things a mechanic can do to clear this code:

There are a number of other routes a technician may take, though, depending on which module reported the problem and its status.

Additional comments for consideration regarding the P0622 code

Aside from taking the trouble codes one at a time, the mechanic must also use resets to ensure that their efforts are actually fixing the problem.

Need help with a P0622 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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