|Trouble Code||Fault Location||Probable Cause|
|P062F||Internal Control Module EEPROM Error||Wiring, incorrect / incompatible software, low or spiking system voltage|
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What Does Code P062F Mean?
OBD II fault code P062F is a generic code that is often defined by most car manufacturers as “Internal Control Module EEPROM Error”, and on applications that use this definition, the code is set when an EEPROM (Electrically Erasable Programmable Read-Only Memory) fault in the PCM (Powertrain Control Module occurs.
However, a major complication with this code is the fact that the memory, or programming that has suffered damage, (or is lost), varies between applications. For instance, on many Toyota products, this code refers to the programming of the fuel injectors, while on some Nissan and Chevrolet products the code refers to issues with the transmission and throttle control programming respectively.
EEPROMS are essentially “bundles” of calibration data programmed into a chip that control various electronic functions on a vehicle. The advantage of this technology lays in the fact that EEPROM’s are integral to the PCM, in the sense that they can be reprogrammed (flashed) without removing the PCM from the vehicle. However, in practical terms, the problem involves determining exactly which EEPROM is defective, and then correcting the root cause of the problem before reflashing the PCM to restore the affected EEPROM’s programming and functionality.
The image above shows the typical size and location of an EEPROM chip on the printed circuit board (PCB) of an automotive PCM. The EEPROM chip is circled in red.
What are the common causes of code P062F?
One common cause of code P062F is the use of performance chips that alter the PCM’s programming to increase engine power. Performance chips and products are not created equal, meaning that some after market performance chips and programs can (and do) fail unexpectedly. Other possible causes could include the following-
- Damaged, burnt, shorted, or corroded wiring and/or connectors
- Use of incorrect or incompatible software in ill-considered attempts to alter the PCM’s calibration
- Low system voltages, or voltage spikes that can (and do) damage some circuits in many PCM’s
What are the symptoms of code P062F?
Typical symptoms of this code could include a stored trouble code and illuminated warning light(s). Other symptoms of this code are mostly make and model specific, and depending on the application, could include non-starting conditions and serious driveability problems. Always consult the manual for the application being worked on for detailed information of possible symptoms of code P062F as it pertains to that application.
How do you troubleshoot code P062F?
SPECIAL NOTES: Simply replacing or reprogramming a PCM is NOT a guaranteed remedy for this code. Take note that diagnostic and repair procedures for code P062F are mostly make and model specific, which means that on some applications the root cause of this code does not always involve PCM failure. Always consult the manual for the application being worked for detailed information in which EEPROM’s are most likely to be affected when code P062F is present. Be aware though that actually testing all relevant circuits to eliminate or confirm sensor, component, or wiring failure(s) as the root cause of P062F can involve resistance, continuity, and ground testing of hundreds of individual circuits.
Therefore, diagnosing and repairing code P062F requires professional grade diagnostic equipment, above average diagnostic skills in general, and expert-level knowledge of the application being worked on in particular. While it is possible to reprogram an automotive PCM on a DIY basis, doing so requires professional grade equipment and LICENSED software obtainable from the manufacturer. Be aware that while unlicensed (pirated) copies of automotive software are available, using such software to reprogram a PCM is strongly discouraged, because it can destroy that PCM. END OF SPECIAL NOTES.
Record all fault codes present, as well as all available freeze frame data. This information could be of use should an intermittent fault be diagnosed later on. Be aware though that many manufacturers use specific generic codes to indicate intermittent EEPROM faults.
NOTE #1: If a code that indicates an intermittent EEPROM fault is present, consult the manual on the correct procedure to clear the code. On some applications this can be done without a scanner, but whatever the method applicable to the application, clear the code and operate the vehicle for at least two complete drive cycles to see if it returns. In many cases, the code may be an artefact of a low system voltage or similar transient issue, and clearing P062F is often sufficient to resolve the problem.
NOTE #2: If the code returns, bear in mind that real-world driving and operating conditions can cause some EEPROM’s to become “sluggish”, in much the same way that a PC becomes sluggish unless the hard drive is defragmented regularly. However, a PCM cannot be defragmented, but in many cases, this code can be resolved simply by reprogramming the PCM, which has the same effect as defragmenting a hard drive. This option should be considered as a first step in the diagnostic and repair procedure, since the process of reprogramming is relatively inexpensive, as opposed to the potentially huge repair bill that comes with attempting to diagnose and repair say, bad connections or abnormal resistances that may, or may not, be present in any one or more of hundreds of circuits.
If the code returns after having completed several drive cycles, resist the temptation to replace the PCM. This is NOT a guaranteed remedy, and besides, the replacement PCM must be programmed before it will work.
Instead, consult the manual on the location of all ground connection points on the vehicle, and perform a thorough visual inspection of all connections, but be aware that it may be necessary to remove seats, carpets, trim panels, and parts of the dashboard to gain access to all ground connections.
Clean and repair ground connections as required, but DO NOT disconnect the battery unless the manual explicitly states that it must be disconnected at this point. While it is true that on some applications it is required to disconnect the battery during the diagnostic process, this is NOT true for all applications, and disconnecting the battery could have fatal consequences for the electrical system on applications where the battery is not required to be disconnected.
When all wiring is checked and reconnected, clear the code, and re-test the system to see if the code returns. If it does, there are two possibilities; either the EEPROM has failed, or a wiring/component failure/malfunction has caused the EEPROM to fail.
Determining which is which is not easy, especially if the PCM has non-stock programming, and unless you possess advanced diagnostic skills, it is strongly recommended that you refer the vehicle for professional diagnosis and repair. At the risk of overstating the case, replacing or reprogramming the PCM is NOT guaranteed to cure the problem.
NOTE: If the PCM programming is known to have been altered for any reason, one possible remedy is to return the programming to stock specifications and settings. In many cases, non-stock performance settings/tuning chips can cause memory loss in some EEPROM’s after some use, but bear in mind that only software obtained from the manufacturer that conforms to the SAE J2534 standard must be used for this to ensure that the PCM is fully compatible with the application.
Short of replacing the PCM (and hoping that doing so will cure the problem), non-professional mechanics have little to no chance to diagnose and repair the underlying cause of P062F, meaning that beyond Step 3, the wisest course of action would be to refer the vehicle to the authorized dealer, or a specialist technician for diagnosis and repair.
NOTE: At this point, replacing the PCM with a used unit might be an option, but bear in mind that the replacement must be from a vehicle that is identical to the problem vehicle in every respect. Pay particular attention to the transmission of the donor vehicle; PCM’s from automatics are programmed differently from PCM’s in manual vehicles, meaning that PCM’s from applications with manual and automatic transmissions are NOT interchangeable.
Codes Related to P062F
Note that some manufacturers, most notably Volkswagen, Audi, and Volvo, have assigned the definition “Internal Contr. Module (EEPROM) Error” to code P1640, instead of the generic code P062F used by all other manufacturers to indicate EEPROM issues.