What does it mean?
This generic powertrain diagnostic trouble code (DTC) generally applies to many OBD-II vehicles. This may include, but is not limited to, Chevrolet, GMC, Dodge, Ram vehicles, etc.
A stored P0612 code means the Powertrain Control Module (PCM) has detected a malfunction in its internal control module. The issue is related to the part 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 often, it is integrated into the PCM. This saves space, time, and money for car manufacturers.
Similarly, the fuel injector control module relay may be an integral part of the PCM or it may be a conventional relay located away from the PCM. Consult a reliable vehicle information source to determine the location of the fuel injector control relay for the specific vehicle.
Whenever the ignition is turned on and the PCM is powered, 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 that the various controllers interact correctly.
When monitoring the fuel injector relay control function, if the PCM detects a problem, a P0612 code will be stored and a Malfunction Indicator Lamp (MIL) may illuminate. Depending on the perceived severity of the malfunction, several failure cycles may be required for the MIL to light up.
A fuel pump control module:
P0612 Fuel Pump Control Module
How serious is this DTC?
Internal control module codes should always be taken seriously. A stored P0612 code could lead to various driving problems, including a no-start condition.
What are some of the symptoms of the code?
Symptoms of a P0612 fault code may include:
- Engine driveability issues
- Reduced engine performance
- Reduced fuel efficiency
- Other stored codes
What are some common causes of the code?
Causes of this code may include:
- Faulty PCM
- PCM programming error
- Faulty PCM power relay
- Open or shorted circuit or connectors in the CAN bus
- PCM power supply failure
- Insufficient control module ground
What are the P0612 troubleshooting steps?
Unfortunately, even the most experienced and well-equipped professional technician may find diagnosing a P0612 code quite challenging. There is also the issue of reprogramming. Without the necessary reprogramming equipment, it will be impossible to replace a faulty controller and perform a successful repair.
If ECM/PCM power codes are present, they must be repaired before attempting to diagnose a P0612.
There are several preliminary tests that can be performed before declaring a controller faulty. A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source will be required.
Connect the scanner to the vehicle’s diagnostic port and retrieve all stored codes and freeze frame data. You’ll want to note this information, just in case the code turns out to be intermittent. After recording all relevant information, clear the codes and test 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 P0612 to be stored may even need to worsen before a diagnosis can be made. If the code resets, continue with this short list of preliminary tests.
When trying to diagnose a P0612, information can be your best tool. Search your vehicle information source for Technical Service Bulletins (TSBs) that correlate the stored code, the vehicle (year, make, model, and engine), and the symptoms presented. If you find the right TSB, it can provide diagnostic information that will significantly assist you.
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.
Use the DVOM to test the controller’s power fuses and relays. Pay special attention to the fuel injector controller relay if it is an external relay. Follow the manufacturer’s recommendations for testing the relay with the DVOM. If the fuel injector control relay is faulty and integrated into the PCM, the PCM must be replaced and reprogrammed. Replace 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 related circuits. Use the DVOM to test ground integrity.
Visually inspect the system controllers for signs of water, heat, or collision damage. Any controller