P0612: Fuel Injector Control Module Relay Control

What Does The P0612 Code Mean?

A stored code P0612 means that the powertrain control module (PCM) has detected an internal control module malfunction. The issue is related to the portion of the PCM that controls the fuel injector control module relay.

In some cases, the fuel injector controller may be separate from the PCM. Most frequently, it is integrated into the PCM. This saves automakers space, time, and money.

Likewise, the fuel injector control module relay may be an integral part of the PCM or it may be a conventional relay that is located away from the PCM. Consult a reliable source of vehicle information to determine the location of the fuel injector control relay for the vehicle in question.

Each time the ignition is turned on and the PCM is energized, multiple 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 that the various controllers are interacting properly.

In monitoring fuel injector relay control function, if the PCM detects a problem, a code P0612 will be stored and a malfunction indicator lamp (MIL) may be illuminated. Depending upon the perceived severity of the malfunction, multiple failure cycles may be necessary for MIL illumination.

What Are The Symptoms Of The P0612 Code?

Symptoms of a P0612 trouble code may include:

• Engine drivability issues
• Reduced engine performance
• Diminished fuel efficiency
• Other stored codes

What Are The Potential Causes Of The P0612 Code?

Causes for this code may include:

• Faulty PCM
• PCM programming error
• Defective PCM power supply relay
• Open or shorted circuit or connectors in the CAN harness
• Failed PCM power source
• Insufficient control module ground

How Serious Is This P0612 Code?

Internal control module codes must always be taken seriously. A stored code P0612 could result in a variety of drivability concerns, including a no-start condition.

How Can You Fix The P0612 Code?

Unfortunately, even the most experienced and well-equipped professional technician may find diagnosing a code P0612 to be quite a challenge. There is also the issue of reprogramming. Without the necessary reprogramming equipment, it will be impossible to replace a defective controller and complete a successful repair.

If ECM/PCM power supply codes are present, they will need to be repaired before attempting to diagnose a P0612.

There are several preliminary tests that can be performed prior to declaring any controller defective. A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of reliable vehicle information will be required.

Retrieve All Stored Codes

Connect the scanner to the vehicle diagnostic port and retrieve all stored codes and freeze frame data. You will want to write this information down, just in case the code proves to be an intermittent one. After recording all pertinent information, clear the codes and test drive the vehicle until the code is reset 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, which caused the P0612 to be stored, may even need to worsen before a diagnosis can be made. If the code is reset, continue with this short list of preliminary tests.

When attempting to diagnose a P0612, information may be your greatest tool. Search your vehicle information source for technical service bulletins (TSB) that parallel the code stored, vehicle (year, make, model, and engine), and symptoms exhibited. If you find the right TSB, it may yield diagnostic information that will aid you in a major way.

Use your source of vehicle information to obtain connector face views, connector pin-out charts, component locators, wiring diagrams, and diagnostic flow charts related to the code and vehicle in question.

Use The DVOM To Test Controller Power Supply Fuses And Relays

Pay particular attention to the fuel injector controller relay if it is an external relay. Follow manufacturers recommendations for testing the relay with the DVOM. If the fuel injector control relay is bad and it is integrated with the PCM, the PCM must be replaced and reprogrammed. Replace blown fuses as required. Fuses should be tested with the circuit loaded.

If all fuses and relays appear to be functioning as intended, a visual inspection of controller related wiring and harnesses is in order. You will also want to check chassis and engine ground junctions. Use your vehicle information source to obtain ground locations for related circuits. Use the DVOM to test ground integrity.

Visually inspect system controllers for signs of water, heat, or collision damage. Any controller that is damaged, especially by water, should be considered defective.

If controller power and ground circuits are intact, suspect a defective controller or a controller programming error. Controller replacement will require reprogramming. In some cases, you may purchase reprogrammed controllers through aftermarket sources.

Other vehicles/controllers will require on-board reprogramming that may only be done through a dealership or other qualified source.

• Unlike most other codes, the P0612 is likely caused by a defective controller or a controller programming error
• Test system ground integrity by connecting the negative test lead of the DVOM to ground and the positive test lead to battery voltage

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> WORKPRO 582-piece Crimp Terminals, Wire Connectors, Heat Shrink Tube, Electrical Repair Kit
>>> ECU
>>> INNOVA 5210
>>> KAIWEETS Digital Multimeter

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

P0612 Fuel Injector Control Module Relay Control, OBD-Codes.