P0626 - Malfunction in the generator excitation circuit

OBD-II Trouble Code - P0626 - Data Sheet

Code P0626 indicates a malfunction in the generator excitation circuit.

Code P0626 is often associated with a DTC P0625.

What does trouble code P0626 mean?

This is a generic Diagnostic Trouble Code (DTC) applicable to many OBD-II vehicles (1996 and newer). This may include, but is not limited to, Ford, Kia, Dodge, Hyundai, Jeep, etc. Despite the general nature, the exact repair steps may vary depending on the model year, make, model and transmission configuration.

A stored code P0626 means the powertrain control module (PCM) has detected a higher than expected voltage signal from the generator field coil circuit. The letter F simply repeats that the field coil control circuit is faulty.

The field coil is probably best recognized by its windings, which are visible through the vents on most alternators. The excitation coil surrounds the generator armature and remains stationary in the generator housing. The armature rotates inside an excitation coil, which is powered by battery voltage. Every time the engine is started, the field coil is energized.

The PCM monitors the continuity and voltage level of the generator excitation circuit whenever the engine is running. The generator field coil is integral to the operation of the generator and the maintenance of the battery level.

If a problem is detected while monitoring the generator excitation circuit, a P0626 code will be stored and a malfunction indicator lamp (MIL) may illuminate. Depending on the perceived severity of the malfunction, multiple failure cycles may be required to illuminate the MIL.

Typical alternator:

What is the severity of this DTC?

A stored P0626 code can result in a variety of handling problems including no starting and / or low battery. It should be classified as heavy.

What are some symptoms of code P0626?

Code P0626 causes the Check Engine light to come on on the car's dashboard. Along with this, the car may experience various symptoms associated with the fact that parts of the transmission do not receive sufficient charge. There may be problems with anti-lock brakes, automatic transmission, traction control, idling and engine operation. Fuel consumption may also be reduced.

Symptoms of a P0626 trouble code may include:

• Charging lamp illumination
• Engine control problems
• Unintentional engine shutdown
• Engine start delay
• Other stored codes

What are some of the common causes for the code?

Reasons for this code may include:

• Open or short circuit in the generator field control circuit
• Blown fuse or blown fuse
• Defective generator / generator
• Defective PCM
• PCM programming error
• Defective generator
• Bad battery
• Damage or corrosion in the generator control module circuit
• Bad wiring somewhere in the car
• Poor communication between generator control module and powertrain control module.

What are some steps to troubleshoot the P0626?

Diagnosing the P0626 code requires a diagnostic scanner, battery / alternator tester, digital volt / ohmmeter (DVOM), and a reliable vehicle information source.

Consult your vehicle information source for technical service bulletins (TSBs) that reproduce the stored code, vehicle (year, make, model and engine) and symptoms detected. If you find a suitable TSB, it can provide useful diagnostics.

Start by connecting the scanner to the vehicle's diagnostic port and retrieving all stored codes and freeze frame data. You will want to write this information down just in case the code turns out to be intermittent. After recording all relevant information, clear the codes and test drive the vehicle until the code is cleared or the PCM enters standby mode. If the PCM enters ready mode, the code is intermittent and harder to diagnose. The condition for which the P0626 was stored may even get worse before a diagnosis can be made. If the code is cleared, continue diagnostics.

Use a battery / alternator tester to test the battery under load and make sure it is sufficiently charged. If not, charge the battery as recommended and check the alternator / generator. Follow the manufacturer's recommended specifications for minimum and maximum output voltage requirements for battery and alternator. If the alternator / generator does not charge, proceed to the next diagnostic step.

Use your vehicle information source to obtain connector views, connector pinouts, component locators, wiring diagrams, and diagnostic block diagrams relevant to the code and vehicle in question.

Check for battery voltage on the alternator / alternator control circuit using the appropriate wiring diagram and your DVOM. If not, check system fuses and relays and replace defective parts if necessary. If voltage is detected at the generator excitation coil control terminal, suspect that the generator / generator is faulty.

• The excitation coil is an integral part of the generator and usually cannot be replaced separately.

How does a mechanic diagnose a P0626 code?

A certified technician will use an advanced OBD-II code scanner and voltmeter to diagnose the problem that is causing the P0626 code to be displayed on the OBD-II system. The technician will be able to review the code and see when it first appeared. After viewing, the technician will reset the error code and test drive the vehicle. If the fault was genuine and not just an intermittent problem, the code will reappear during the test.

If this happens, the circuit will be checked for signs of damage or corrosion. It may be necessary to replace the wiring harness around the excitation circuit of the generator along with parts of the circuit itself. A voltmeter will be used to compare the power going through the circuit with the factory settings.

Common Mistakes When Diagnosing Code P0626

Engine performance problems resulting from an electrical underpower problem are often corrected before a fault in the generator field is diagnosed. This means time is wasted diagnosing poor fuel delivery, ignition timing, or problems with the brakes or traction control. These problems may simply disappear after repairing the excitation circuit of the generator.

How serious is the P0626 code?

While this problem may not cause engine failure, and although a P0626 code may not stop the engine, this should be taken seriously. This is moderately serious and will continually cause other problems that can lead to costly repairs down the road.

What repairs can fix code P0626?

The most common repair to resolve code P0626 is as follows:

• Repair or replace the generator excitation circuit
• Replace wiring harness around generator and generator control module.
• Repair or replace wiring and connections around the powertrain control module.
• Replace car battery

Additional comments to consider regarding code P0626

Insufficient electrical power due to a fault in the generator excitation circuit can cause a wide range of problems that may or may not occur all the time. Because of this, an OBD-II system can save a lot of time and money by showing the technician the root of the problem. Otherwise, other systems can be diagnosed for related problems when they are in perfect working order.

What is P0626 Engine Code [Quick Guide]

Need more help with the P0626 code?

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NOTE. This information is provided for informational purposes only. It is not intended to be used as a repair recommendation and we are not responsible for any action you take on any vehicle. All information on this site is protected by copyright.