Fix P062F: Mechanic’s solutions that WORKED

The code P062F: Internal Control Module EEPROM Error points out a fault in the vehicle’s internal control module, particularly with the EEPROM component of the ECM. This issue is most likely caused by ECM failures, power supply problems, or electrical connection issues.

P062F quick overview

Meaning	P062F: Internal Control Module EEPROM Error
Is it serious?	This code can be serious as it indicates a fundamental problem with the vehicle’s Engine Control Module (ECM), potentially affecting the vehicle’s performance and drivability.
Possible causes	– EEPROM (Electrically Erasable Programmable Read-Only Memory) failure in the ECM – Faulty ECM or issues with its software – Poor electrical connections to the ECM – Power supply problems to the ECM
How to diagnose?	Check ECM Connections: Inspect the connections to the ECM for any looseness or corrosion. Inspect Power Supply: Verify that the ECM is receiving proper power supply and ground. Reprogram ECM: Consider reprogramming or updating the ECM software. Replace ECM if Needed: If reprogramming doesn’t resolve the issue, replacement of the ECM may be necessary. Consult Technical Bulletins: Check for any manufacturer’s bulletins or recalls related to ECM issues.

How to fix P062F – learn from mechanics

I looked into P062F 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: Chevrolet

Vehicle Information: 2007 Chevrolet HHR LT 2.2L, MIL Lamp on

Issue + Repair History:

• Vehicle arrived from a body shop to turn off MIL.
• Found P062f code in TCM, replaced TCM and reflashed, but MIL returned.
• Found P062f in ECM, replaced and reflashed ECM, yet the light returned.
• Checked for ground and power failures, all were good.
• Related repair history: Front crash damage repair, MIL not on before crash.

Other OBD2 Codes + Test Results:

• P062f – TCM long term memory loss
• P062f – ECM long term memory loss
• Grounds: Good
• Power supply: 12.6v

Suggestions to Fix Issue:

• Crash may have caused pinched wire or poor body ground contact.
• Load test power and ground circuits.
• Load test ECM grounds at specific connectors.
• Check for airbag codes, which might require SDM and crash sensor replacement.
• Ensure scanning of all controllers for codes.

Final Fix: The problem was resolved by replacing the ECM again with a new one, after initially receiving a bad new ECM.

Case #2: Infiniti

Vehicle Information: 2015 Infiniti QX60 3.5L, No Start

Issue + Repair History:

• Previous shop installed an alternator and damaged the wire harness, shorting out the PCM.
• Technician replaced the engine wire harness and installed a new PCM from Infiniti.
• Uncertain if PCM needs programming with NERS or just VIN entry and key learning with Autel.

Other OBD2 Codes + Test Results:

• P062f – Control module
• Wires – Shorted

Suggestions to Fix Issue:

• New PCM likely needs full programming, not just VIN writing and key registration.
• The ECM will come blank and requires programming with the correct TYPE ID, VIN writing, key registration, IAVL (Idle Air Volume Learning) performance, and possibly throttle position learning.

Final Fix: After replacing the wire harness and alternator, the code never reset, and the vehicle runs fine, suggesting the programming concerns might not have been necessary in this case.

Case #3: Chevrolet

Vehicle Information: 2008 Chevrolet Silverado 2500 HD WT 6.6L, No Start/No Crank

Issue + Repair History:

• No start/no crank condition; dash lights go out when key is turned, engine light stays on.
• Hard code P062F (EEPROM error in engine computer) returns instantly when cleared.
• OnStar disabled/partially bypassed; GPS input and microphone unplugged.
• Vehicle ran fine for a month after OnStar disconnection; OnStar light changed from green to red.
• Possible link between OnStar disconnection and the no start condition.

Other OBD2 Codes + Test Results:

• P062f – Internal EEPROM error (engine computer)

Suggestions to Fix Issue:

• The vehicle likely needs ECM reprogramming, possibly under warranty.
• EEPROM error indicates a need for a reflash before replacing the module.
• Customer should check for any recall or warranty coverage related to this issue.
• OnStar disconnection should not impact starting; focuses on ECM issue.

Final Fix:

• A service bulletin (number 08142a) addressed this issue.
• Reflashing the engine control module with TechII and GM’s TIS to WEB resolved the problem.
• The vehicle was under warranty, but the customer chose to have the technician fix it.

Case #4: Chevrolet

Vehicle Information: 2007 Chevrolet Cobalt LS 2.2L, MIL Lamp on

Issue + Repair History:

• Initially had P0604 control module RAM fault.
• Recommended ECM replacement after checking ECM powers and grounds.
• Installed two used ECMs, reprogrammed with TIS, changed VIN, but resulted in P062F internal EEPROM error code.
• Completed crank variation relearn; no TAC relearn required for this model.
• No faults in TCM; even tried reprogramming TCM.

Other OBD2 Codes + Test Results:

• P062f – Internal EEPROM Error

Suggestions to Fix Issue:

• Possibility of faulty PCM; suggestion to go for AC Delco remanufactured part.
• P062F could be due to incomplete/corrupted files or improper crank relearn.
• EEPROM error might require checking both ECM and TAC module calibrations.
• Consider using a new or remanufactured ECM rather than a used one.
• Check if the TAC calibration and ECM software are in sync.
• Ensure all grounds are checked properly.

Final Fix:

• After consultation and not finding a solution, technician contacted Drew Technology’s tech help and AC Delco TIS tech help.
• AC Delco TIS suspected a faulty used ECM but did not think it was a programming issue.
• The customer, a used car lot, declined the new ECM and chose to sell the car with the engine light on.

Case #5: Chevrolet

Vehicle Information: 2008 Chevrolet Express 2500 6.6L, Starting issues

Issue + Repair History:

• Vehicle experiencing a no-start issue, suspected Passlock lock-up.
• Codes present: P062F (long term memory) and P0633 (Passlock not learned).
• Able to crank the van from the relay but it won’t start.
• New ignition switch installed, but issue persists.
• Can communicate with all modules; transmission indicates correct gear, but no start signal received.
• History of battery going dead; vehicle was towed in with a very loose battery.
• Concern about Passlock system potentially forgetting its settings.

Other OBD2 Codes + Test Results:

• P062f – EEPROM long term memory error
• P0633 – Passlock not learned

Suggestions to Fix Issue:

• Try relearning the key with a specific procedure: key on (not start) for 10 minutes, then off, repeated three times.
• Suggestion that the issue may be related to a dead battery causing memory loss.
• There is a GM bulletin recommending ECM programming for this exact problem.

Final Fix:

• The vehicle was taken before the technician could apply the suggested fix.
• The technician appreciated the advice and plans to use it in the future.

Advice	Description of Diagnostic Step
Reprogramming ECM	Update the Engine Control Module software to resolve potential issues.
Check for Grounds and Powers	Verify the integrity of ECM grounds and power connections.
Use New or Remanufactured ECM	Consider using new or remanufactured ECMs instead of used ones.
Perform Key Relearn Process	If applicable, conduct a key relearn process to reset security settings.
Consult Technical Bulletins	Check manufacturer’s service bulletins for known issues and fixes.