P06B8 Internal Control Module Non-Volatile Random Access Memory (NVRAM) Error
OBD-II Trouble Code Technical Description
Internal Control Module Non-Volatile Random Access Memory (NVRAM) Error
What does that mean?
This generic powertrain diagnostic trouble code (DTC) typically applies to many OBD-II vehicles. That may include but is not limited to vehicles from Ford, Mazda, etc.
When a code P06B8 is stored, it means that the powertrain control module (PCM) has detected an internal processor performance error with non-volatile access memory (NVRAM). Other controllers may also detect an internal PCM performance error (with NVRAM) and cause a P06B8 to be stored.
Internal control module monitoring processors are responsible for various controller self-test duties and overall internal control module accountability. NVRAM input and output signals are subject to self-test and are monitored constantly by the PCM and other related controllers. The transmission control module (TCM), traction control module (TCSM), and other controllers also interact with NVRAM.
In automotive applications, NVRAM is used to help retain data memory when power is shut off to the PCM. NVRAM is integrated into the PCM. Even though the NVRAM is capable of more than 1-million programming changes, and is designed to last for hundreds-of-years, it can be sensitive to excessive heat and moisture.
Whenever the ignition is on and the PCM is energized, NVRAM self-tests are initiated. In addition to running internal controller self-tests, the controller area network (CAN) also compares signals from each individual module to ensure that each controller is functioning properly. These tests are performed simultaneously.
If the PCM detects an internal discrepancy in the NVRAM processor, a code P06B8 will be stored and a malfunction indicator lamp (MIL) may be illuminated. Additionally, if the PCM detects a problem between any of the on-board controllers, which would indicate an internal knock sensor system error, a code P06B8 will be stored and a malfunction indicator lamp (MIL) may be illuminated. Multiple failure cycles may be necessary for MIL illumination, depending upon the perceived severity of the malfunction.
Example photo of a PCM:
What is the severity of this DTC?
Internal control module processor codes should be categorized as severe. A stored code P06B8 could result in a variety of drivability concerns.
What are some of the symptoms of the code?
Symptoms of a P06B8 trouble code may include:
A variety of engine drivability symptoms Other stored diagnostic trouble codesWhat are some of the common causes of the code?
Causes for this code may include:
Bad PCM or a PCM programming error Open or shorted circuit or connectors in the CAN harness Insufficient control module groundWhat are some P06B8 troubleshooting steps?
Even to the most experienced and well-equipped professional technician, diagnosing a code P06B8 can prove 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 there are ECM/PCM power supply codes present, they will obviously need to be rectified before attempting to diagnose a P06B8.
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.
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
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