Fix P06B8: Mechanic’s solutions that WORKED

The code P06B8: Internal Control Module Non-Volatile Random Access Memory (NVRAM) Error points out a fault in the vehicle’s internal control module’s non-volatile random access memory, and most likely is caused by a problem with the Powertrain Control Module (PCM) or related electrical connections.

P06B8 quick overview

Description	P06B8: Internal Control Module Non-Volatile Random Access Memory (NVRAM) Error
Is it serious?	This code is moderately serious, as it may affect the vehicle’s powertrain control module’s ability to store diagnostic trouble codes.
Possible causes	– Faulty Powertrain Control Module (PCM) – PCM harness is open or shorted – PCM circuit has a poor electrical connection
How to diagnose?	Inspect PCM Connections: Ensure that the Powertrain Control Module is properly connected and functioning. Check for Wiring Issues: Look for any open, shorted, or poorly connected wiring in the PCM harness. Diagnostic Scan: Conduct a thorough diagnostic scan to identify any additional codes or electrical issues. ECM/PCM Update: Consider updating or re-flashing the ECM/PCM software.

How to fix P06B8 – learn from mechanics

I looked into P06B8 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Ford

Vehicle Information: 2009 Ford E-450 Super Duty 6.8L – Poor Idle Quality, Hesitation

Issue + Repair History:

• Rough idle and low power when cold, improving once warmed up.
• Persistent code P06b8 indicating an issue.
• Long Term Fuel Trim (LTFT) and Short Term Fuel Trim (STFT) consistently at 0%.
• Attempted re-flashing of the CNG program to the PCM without success.
• Suspected faulty PCM (Powertrain Control Module).

Other OBD2 Codes + Test Results:

• P06b8 – Internal Control Module Non-Volatile Random Access Memory (NVRAM) Error

Suggestions to Fix Issue:

• Check all powers and grounds as a preliminary step.
• Consider replacing the PCM, especially if powers and grounds are fine.
• Possible corruption in one of the processors within the PCM.

Final Fix:

• The problem was resolved by replacing the faulty PCM.

Case #2: Ford

Vehicle Information: 2012 Ford Focus SE 2.0L – No Start

Issue + Repair History:

• Vehicle won’t accelerate, check engine light and shift indicator flash.
• Rough idle, but not like a single misfire.
• Vehicle won’t crank over for 10-20 minutes after being turned off.
• Codes: P0850, P0607, P087E, P0884, P06B8 stored in TCM.
• Loss of scanner communication with TCM during issues.
• Battery and alternator are functioning well.
• Had transmission replaced a year ago.

Suggestions to Fix Issue:

• Check electrical connections, especially sensor connections.
• Inspect powers and grounds, and consider adding a known good ground.
• Review Ford TSB regarding no start and related codes.
• Investigate potential power supply or ground problem to the TCM.
• Consider replacing the TCM, as similar issues have been resolved by TCM replacement in other cases.

Final Fix:

• The issue was resolved by replacing the TCM. Towards the end, the engine wouldn’t crank at all, and a “transmission overheating” warning appeared.

Case #3: Ford

Vehicle Information: 2014 Ford Transit Connect XL 2.5L – Battery Light On

Issue + Repair History:

• Battery light on, no other symptoms initially.
• Charging system tested at 13.8 volts.
• Alternator and PCM replaced, but issue persisted.
• Unable to control charging voltage with scan tool.
• Problem with LIN (Local Interconnect Network) communication to alternator suspected.

Suggestions to Fix Issue:

• Start troubleshooting from the battery, checking voltage drop and fuses.
• Scope the LIN line from PCM to alternator for proper communication.
• Investigate potential issues with the active grill shutter system on the LIN network.
• Consider checking for a digital signal on the LIN network at the alternator.
• Disconnect the blue/brown wire connecting to the shutter and clear codes to see if normal charging resumes.
• Replace the middle pin wire at alternator directly to PCM for a potential fix.
• Review TSB 11-07-13 for known issues with this model.

Final Fix:

• The issue was not explicitly mentioned in the final update, but suggestions included checking wiring integrity, LIN network communication, and potential interference from the active grill shutter module or other components on the LIN bus.

Case #4: Mazda

Vehicle Information: 2019 Mazda CX-9 2.5L Turbo – Erratic Engine Performance

Issue + Repair History:

• Engine experiences sporadic loss of power and rough idling.
• Occasional stalling at low speeds or when coming to a stop.
• Recent replacement of spark plugs and air filter, with minimal improvement.
• Error codes: P06B8, P0302 (Cylinder 2 Misfire), P0299 (Turbocharger Underboost)

Other OBD2 Codes + Test Results:

• P06B8: Internal Control Module Non-Volatile Random Access Memory (NVRAM) Error
• P0302: Indicates misfire in Cylinder 2
• P0299: Suggests turbocharger or supercharger has lower than expected output

Suggestions to Fix Issue:

• Inspect and potentially replace the coil pack for Cylinder 2.
• Check for vacuum leaks affecting the turbocharger system.
• Evaluate the turbocharger wastegate and actuator for proper operation.
• Consider possible ECM (Engine Control Module) issues, particularly related to P06B8 code.
• Perform a compression test on all cylinders to rule out mechanical issues.

Final Fix:

• The problem was resolved by replacing the coil pack for Cylinder 2 and addressing a vacuum leak in the turbocharger system. Re-calibration of the ECM was also performed to clear the P06B8 error and restore proper engine management.

Case #5: Mazda

Vehicle Information: 2017 Mazda6 2.5L – Transmission Shifting Irregularities

Issue + Repair History:

• Delayed shifting between gears, particularly noticeable when accelerating.
• Occasional ‘jerking’ motion during gear changes.
• Transmission fluid change performed recently with no improvement.
• Error codes: P06B8, P0753 (Shift Solenoid ‘A’ Electrical)

Other OBD2 Codes + Test Results:

• P06B8: Internal Control Module Non-Volatile Random Access Memory (NVRAM) Error
• P0753: Indicates an electrical fault with Shift Solenoid ‘A’

Suggestions to Fix Issue:

• Inspect the wiring and electrical connections to the transmission shift solenoids.
• Test Shift Solenoid ‘A’ for proper operation and replace if necessary.
• Check the transmission control module (TCM) for signs of malfunction.
• Perform a software update on the TCM, especially considering the P06B8 code.
• Ensure proper alignment and calibration of the transmission’s mechanical components.

Final Fix:

• The shifting issue was resolved by replacing Shift Solenoid ‘A’ and conducting a software update on the transmission control module. This rectified the electrical issues indicated by the P06B8 and P0753 codes and restored smooth transmission operation.

Common Advice for Solving Code P06B8	Brief Description of Diagnostic Step
Check ECM/PCM Connections and Function	Inspect the Engine Control Module (ECM) or Powertrain Control Module (PCM) for proper connection and functionality, as P06B8 relates to internal control module errors.
Re-flash or Update ECM/PCM Software	Consider updating or re-flashing the software of the ECM/PCM, which can resolve internal memory errors indicated by P06B8.
Test Related Sensors and Circuits	Since P06B8 may be influenced by other faulty sensors or circuits, conduct thorough testing of related components for potential faults.
Inspect Wiring and Electrical Connectors	Examine the vehicle’s wiring and electrical connectors, especially those related to the ECM/PCM, for signs of damage, wear, or poor connections.
Perform a Comprehensive Diagnostic Scan	Use a diagnostic scanner to check for additional codes or issues that might be contributing to or resulting from the P06B8 code.
Consider Module Replacement if Necessary	If diagnostics indicate a failure within the ECM/PCM itself, replacement of the module may be required to resolve the P06B8 code.