P0626 OBD-II Trouble Code: Generator Field/F Terminal Circuit High

P0626 code definition

The P0626 code identifies a fault on the generator field circuit

The P0626 code is often associated with the P0625 trouble code

What the P0626 code means

The P0626 code is the OBD-II generic code for a fault that is detected on the generator field circuit. This is most likely due to a faulty alternator or generator control module. The Powertrain control module has detected a fault that may involve other vital parts of the powertrain not receiving adequate electrical power. Other modules within the OBD-II system can detect this fault aside from the powertrain control module. This includes the instrument panel control module, traction control module, and antilock brake control module.

What causes the P0626 code?

The fault detected on the generator field code may have several causes:

• Faulty alternator
• Bad battery
• Damage or corrosion on generator control module circuit
• Bad wiring somewhere in the vehicle
• Poor communication between generator control module and powertrain control module

What are the symptoms of the P0626 code?

The P0626 code will cause the Check Engine Light to be illuminated on the vehicle’s dashboard. Along with this, the vehicle may experience a variety of symptoms related to parts of the powertrain not receiving adequate charge. There may be issues with the anti-lock brakes, automatic transmission, traction control, idling, and engine performance. Fuel economy may also drop.

How does a mechanic diagnose the P0626 code?

A certified technician will use an advanced OBD-II code scanner and a voltmeter to diagnose the issue that cause the P0626 code to be indicated within the OBD-II system. The technician will be able to look at the code and see when it first appeared. After viewing this, the technician will reset the error code and test drive the vehicle. If the fault was genuine and not just an intermittent problem, then the code will reappear during the test.

If this happens, the circuitry will be inspected for signs of damage or corrosion. The wiring harness around the generator field circuit may need to be replaced along with pieces of the circuitry itself. A voltmeter will be used to compare the power going through the circuit to the factory settings.

Common mistakes when diagnosing the P0626 code

Engine performance problems that pop up due to the problem of insufficient electrical power are often repaired before the fault on the generator field is diagnosed. This means that time is wasted diagnosing poor fuel delivery, ignition timing or issues with the brakes or traction control. These issues may just go away once the generator field circuit is repaired.

How serious is the P0626 code?

While this problem may not cause engine failure, and while the P0626 code may not be able to shut down the engine, this could should still be taken seriously. It is moderately serious and will persistently cause other issues that could lead to costly repairs down the road.

What repairs can fix the P0626 code?

The most common repairs to address the P0626 code are as follows:

• Repair or replace generator field circuit
• Replace wiring harness around alternator and generator control module
• Repair or replace wiring and connections around powertrain control module
• Replace vehicle battery

Additional comments for consideration regarding the P0626 code

Insufficient electrical power due to a fault on the generator field circuit can cause a wide variety of problems that may or may not appear consistently. Because of this, the OBD-II system can save lots of time and money by showing the technician the root of the problem. Otherwise other systems may be diagnosed for related issues when they are in perfect working order.

Need help with a P0626 code?

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