What does it mean?
This is a generic diagnostic trouble code (DTC) for the powertrain and generally applies to OBD-II vehicles. This may include, but is not limited to, vehicles from Buick, Chevy, GMC, Ford, Toyota, Nissan, Mercedes, Honda, Cadillac, Suzuki, Subaru, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.
When a P062F code is stored, it means that the Powertrain Control Module (PCM) has detected an internal performance error with the Electrically Erasable Programmable Read-Only Memory (EEPROM). Other controllers may also detect an internal PCM performance error (in the EEPROM) and cause a P062F to be stored.
The internal control module monitoring processors are responsible for various controller self-test tasks and the overall responsibility of the internal control module. EEPROM input and output signals are self-tested and are constantly monitored by the PCM and other associated controllers. The Transmission Control Module (TCM), Traction Control System Module (TCSM), and other controllers also interact with the EEPROM.
In automotive applications, EEPROM provides a way to read, erase, and rewrite small amounts (bytes) of programmable memory. Using specific programming, the EEPROM (or any part of the EEPROM) can be erased and rewritten in sequence. The EEPROM is a bank of transistors consisting of three parts. It is generally removable and locks into a specially designed socket inside the PCM. When a faulty PCM is replaced, the EEPROM usually must be removed and reused in the new PCM. The EEPROM and the new PCM will need to be programmed as a unit. Even though the EEPROM is capable of more than a million programming changes and is designed to last for hundreds of years, it can be sensitive to excessive heat and humidity.
Whenever the ignition is turned on and the PCM is powered up, EEPROM self-tests are initiated. In addition to running internal controller self-tests, the Controller Area Network (CAN) also compares the signals from each individual module to ensure each controller is functioning correctly. These tests are performed simultaneously.
If the PCM detects anomalies in EEPROM functionality, a P062F code will be recorded and a Malfunction Indicator Lamp (MIL) may be illuminated. Additionally, if the PCM detects a problem between any of the onboard controllers, which would indicate an internal EEPROM error, a P062F code will be stored and a Malfunction Indicator Lamp (MIL) may be illuminated. Multiple failure cycles may be required for the MIL to illuminate, depending on the perceived severity of the malfunction.
Photo of a PCM with the cover removed:
How severe is this DTC?
Internal control module processor codes should be classified as severe. A stored P062F code can lead to various driving issues.
What are some of the symptoms of the code?
Symptoms of a P062F fault code may include:
- Many engine/transmission driving problems
- No-start condition
- Reduced fuel efficiency
- Engine stalling or dying at idle
- Lack of cooling fan operation
What are some common causes of the code?
Causes of this P062F DTC code may include:
- Faulty controller or programming error
- Overheated PCM
- Water damage
- A faulty controller power relay or blown fuse
- Open or shorted circuit or connectors in the CAN bus
- Insufficient control module ground
- Faulty EEPROM
What are the P062F troubleshooting steps?
Even for the most experienced and well-equipped professional technician, diagnosing a P062F code can be very 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 will obviously need to be corrected before attempting to diagnose a P062F.
Several preliminary tests can be performed before declaring an individual controller faulty. A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information will be necessary.
Connect the scanner to the vehicle’s diagnostic port and retrieve all stored codes and freeze frame data. You will want to note this information, just in case the code proves 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 P062F 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 P062F, information can be your best tool. Consult 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 specific code and vehicle.
Use the DVOM to test the controller power fuses and relays. Test and 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 junctions. Use your vehicle information source to obtain ground locations for the related circuits. Use the DVOM to test ground integrity.
Visually inspect the system controllers for signs of water, heat, or collision damage. Any damaged controller, especially by water, should be considered faulty.
If the controller power and ground circuits are intact, suspect a faulty controller or a controller programming error. Replacing the controller will require reprogramming. In some cases, you can purchase pre-programmed controllers through aftermarket sources. Other vehicles/controllers will require onboard reprogramming that can only be performed by a dealership or another qualified source.
Unlike most other codes, P062F is likely caused by a faulty controller or a controller programming error
Test the system ground integrity by connecting the DVOM’s negative test lead to ground and the positive test lead to battery voltage