P068A ECM/PCM Power Relay De-Energized Performance - Too Early

The P068A trouble code is a generic OBD-II diagnostic trouble code associated with the ECM/PCM power relay.

P068A – ECM/PCM Power Relay De-Energized Performance – Too Early

This code means that the engine control module has detected that the ECM/PCM power relay switched off earlier than expected.

The ECM/PCM depends on a stable electrical power supply to operate the engine management system. A power relay is used to supply voltage to the control module and, depending on the vehicle, other engine-management components.

When the ignition is switched off, the ECM/PCM does not always shut down immediately. It may remain powered for a short period while it saves data, completes internal routines, communicates with other modules, or performs emissions-related functions.

With P068A, the module detects that its power supply was de-energized too soon.

This is primarily a power supply and relay control problem, not necessarily a defective ECM/PCM.

What Does P068A Mean?

P068A can be understood as:

P = Powertrain
0 = Generic OBD-II code
6 = Computer output/control-related fault
8A = Specific ECM/PCM power relay condition

The important phrase is:

ECM/PCM Power Relay De-Energized Performance – Too Early

In simple terms:

The ECM/PCM lost power earlier than it expected.

What Does "De-Energized Too Early" Mean?

The ECM/PCM power relay normally remains energized for the amount of time required by the vehicle's control strategy.

After the ignition is switched off, the ECM/PCM may continue operating briefly.

For example, it may:

• Save learned values

• Store diagnostic information

• Complete shutdown procedures

• Communicate with other modules

• Perform emissions-related tasks

• Maintain certain circuits temporarily

If the power relay opens prematurely, the ECM/PCM may detect an abnormal shutdown and store P068A.

This can happen because of:

• A failing power relay

• Low battery voltage

• Poor relay contacts

• Ignition-switch problems

• Wiring problems

• Poor grounds

• Voltage drops

• A relay-control problem

• Software issues

• Communication problems

What Is the ECM/PCM Power Relay?

The ECM/PCM power relay is an electrically controlled switch that supplies power to the engine control module.

The terminology varies by manufacturer:

• ECM Power Relay

• PCM Power Relay

• Engine Control Relay

• Main Relay

• ECU Power Relay

• EFI Main Relay

The relay is normally controlled by the vehicle's electrical system or control modules.

Its purpose is to allow a relatively low-current control signal to switch power to the ECM/PCM and related circuits.

Why Does the ECM/PCM Need a Shutdown Period?

Modern engine control modules are not always designed to shut down the instant the ignition is turned off.

After key-off, the module may need to:

• Save operating data

• Complete internal calculations

• Record diagnostic information

• Communicate with other modules

• Complete actuator routines

• Maintain emissions-related systems

• Store adaptive values

If power is removed prematurely, the module can detect an abnormal shutdown.

Symptoms of P068A

Possible symptoms include:

• Check Engine Light

• Engine starting problems

• Intermittent no-start condition

• Engine stalling

• Engine shutting off unexpectedly

• Multiple warning lights

• Intermittent electrical problems

• Loss of communication with the ECM/PCM

• Random diagnostic trouble codes

• Battery drain in some cases

• Rough or abnormal operation

• Vehicle behaving normally after restarting

Some vehicles may have only the Check Engine Light and no obvious drivability symptoms.

Can P068A Prevent the Engine From Starting?

Yes, potentially.

If the ECM/PCM does not receive stable power, it may not be able to control:

• Fuel injection

• Ignition

• Throttle

• Sensors

• Communication

• Engine starting functions

However, P068A does not automatically mean that the vehicle will have a no-start condition.

Can P068A Cause Stalling?

Yes.

If ECM/PCM power is interrupted while the engine is operating, the engine controller can temporarily shut down.

This can result in:

• Engine stalling

• Loss of throttle control

• Loss of fuel injection

• Loss of ignition control

• Multiple warning lights

An intermittent relay or power connection is particularly capable of producing an intermittent stall.

Is P068A Serious?

Yes, it should be taken seriously.

The ECM/PCM is one of the most important control modules in the vehicle.

An unstable power supply can cause unpredictable behavior.

Possible consequences include:

• No-start condition

• Stalling

• Loss of engine control

• Multiple unrelated trouble codes

• Intermittent electrical failures

If the vehicle is stalling while driving, it should not be considered safe to continue driving until the problem is diagnosed.

Common Causes of P068A

Weak or failing battery

Low battery voltage can cause abnormal relay operation.

Faulty ECM/PCM power relay

The relay may open earlier than expected.

Worn relay contacts

Internal contact resistance can cause voltage instability.

Poor relay socket connection

A loose terminal can intermittently interrupt ECM/PCM power.

Corroded terminals

Corrosion can increase resistance and cause voltage drops.

Ignition-switch problem

An ignition switch or ignition-control circuit may incorrectly remove the relay command.

Damaged wiring

A broken or partially broken wire can interrupt the power supply.

Poor ground connection

A bad ground can cause abnormal module voltage and relay behavior.

Low charging-system voltage

A failing alternator or charging system can cause voltage instability.

Battery terminal problems

Loose or corroded battery terminals can interrupt power.

Fuse-box problems

Heat, corrosion or water intrusion can affect the relay circuit.

CAN communication problems

Communication issues between modules can sometimes accompany power-management problems.

Software or calibration issue

In some applications, the ECM/PCM software may incorrectly interpret the relay shutdown timing.

Aftermarket electrical accessories

Poorly installed accessories can interfere with ignition or power-management circuits.

Can a Weak Battery Cause P068A?

Yes.

A weak battery can cause abnormal voltage conditions during:

• Engine starting

• Ignition switching

• Module shutdown

• Electrical load changes

The ECM/PCM may interpret these voltage fluctuations as an abnormal power-relay shutdown.

Battery condition should therefore be checked before replacing expensive components.

Can a Bad Alternator Cause P068A?

Yes, indirectly.

A failing alternator can produce:

• Low charging voltage

• Voltage fluctuations

• Electrical instability

These conditions can affect ECM/PCM power management.

Check charging-system voltage and alternator performance before condemning the relay or ECM.

Can a Bad Relay Cause P068A?

Yes.

The ECM/PCM power relay is one of the first components that should be inspected.

A relay may:

• Open prematurely

• Have worn contacts

• Have excessive internal resistance

• Become heat-sensitive

• Intermittently lose contact

A relay that works correctly when cold may still fail after heating up.

Can a Bad Ignition Switch Cause P068A?

Yes, depending on the vehicle.

If the ignition switch or ignition-control circuit removes the ECM/PCM relay command too early, the module may lose power before completing its normal shutdown process.

This is particularly worth investigating if P068A appears together with other ignition-related electrical problems.

Can a Bad Ground Cause P068A?

Yes.

The ECM/PCM requires stable power and ground connections.

A poor ground can cause:

• Voltage fluctuations

• Module resets

• Communication faults

• Relay-control problems

• Random diagnostic codes

Ground connections should therefore be checked carefully.

Can a Blown Fuse Cause P068A?

A completely blown ECM/PCM power fuse will generally cause more obvious problems, such as a no-start condition or loss of module communication.

However, a poor fuse connection, damaged fuse terminal or intermittent power connection can contribute to ECM/PCM power problems.

Can P068A Be Caused by Wiring?

Yes.

Wiring faults can be particularly difficult because the problem may be intermittent.

Inspect for:

• Broken wires

• Chafed insulation

• Loose terminals

• Corrosion

• Melted wiring

• Poor previous repairs

• Water intrusion

• Loose ground connections

How to Diagnose P068A

A systematic electrical diagnosis is important.

1. Scan all modules

Do not look at P068A alone.

Check for additional codes involving:

• Battery voltage

• Ignition

• ECM/PCM communication

• CAN communication

• Power supply

• Immobilizer

• Other control modules

Additional codes may reveal the original problem.

2. Check battery condition

Measure battery voltage and perform a proper battery test.

A battery can show acceptable voltage at rest but still fail under load.

3. Check battery terminals

Inspect for:

• Corrosion

• Loose connections

• Damaged terminals

• Poor ground connections

A voltage-drop test can help identify high-resistance connections.

4. Check charging-system voltage

Verify that the alternator is producing the correct voltage under the manufacturer's specified conditions.

Look for excessive voltage fluctuations.

5. Locate the ECM/PCM power relay

Use the vehicle-specific wiring diagram to identify:

• Relay power terminals

• Relay control terminals

• ECM/PCM power output

• Ignition input

• Related fuses

Do not assume the relay location or wiring configuration is the same on every vehicle.

6. Inspect the relay

Check:

• Correct relay part number

• Relay condition

• Terminal condition

• Signs of overheating

• Corrosion

• Loose contacts

If appropriate, the relay can be tested according to manufacturer specifications.

7. Inspect the relay socket

The socket can be just as important as the relay itself.

Look for:

• Loose terminals

• Burn marks

• Melted plastic

• Corrosion

• Water intrusion

8. Check ECM/PCM power supply

Measure voltage at the ECM/PCM power input.

Verify that the module receives stable power during:

• Ignition ON

• Engine starting

• Engine running

• Ignition OFF

• The normal shutdown period

This is particularly important with P068A.

9. Monitor power during shutdown

Using an appropriate diagnostic tool or oscilloscope, observe the ECM/PCM power supply after switching the ignition off.

The goal is to determine whether the relay actually de-energizes too early.

10. Check the relay control signal

Determine which module or circuit controls the ECM/PCM power relay.

Verify that the relay command remains active for the correct period.

11. Check ignition-switch operation

If the ignition switch supplies the relay command, verify that its signal behaves correctly during key-off.

12. Check grounds

Inspect and voltage-drop test:

• Battery negative connection

• Engine ground

• Chassis ground

• ECM/PCM ground

• Fuse-box grounds

13. Check wiring continuity and resistance

Inspect the wiring between:

• Relay

• Fuse box

• ECM/PCM

• Ignition circuit

• Ground points

• Related modules

However, remember that a simple continuity test may not reveal an intermittent fault.

14. Check CAN communication

If multiple communication codes are stored, investigate the CAN network.

A power interruption to one module can sometimes create a large number of communication-related codes.

15. Check for software updates

If the electrical system is functioning correctly, check whether the manufacturer has released an ECM/PCM software update related to power management or shutdown behavior.

16. Evaluate the ECM/PCM last

Only after the power supply, relay, wiring, grounds and control signals have been proven correct should an ECM/PCM internal problem be considered.

How to Diagnose an Intermittent P068A

Intermittent P068A faults can be challenging.

A good strategy is to monitor:

• Battery voltage

• ECM/PCM voltage

• Relay control voltage

• Ignition signal

• Ground voltage drop

during the exact conditions when the code appears.

An oscilloscope can be particularly useful for capturing a brief power interruption that a conventional multimeter may miss.

Can P068A Be Caused by a Loose Battery Terminal?

Yes.

A loose battery connection can momentarily interrupt power to multiple vehicle systems.

This may create:

• ECM resets

• Communication codes

• Clock or memory resets

• No-start conditions

• Random warning lights

Always inspect the battery connections before performing expensive electronic repairs.

Can P068A Be Caused by a Bad Fuse Box?

Yes.

A damaged fuse/relay box can cause:

• Poor relay contact

• Internal corrosion

• Heat-related intermittent faults

• Voltage drops

• Power interruptions

Water intrusion around the fuse/relay box is especially important to investigate.

Can P068A Be Caused by Aftermarket Equipment?

Yes.

Poorly installed:

• Remote starters

• Alarm systems

• Audio equipment

• Tracking devices

• Lighting systems

• Other electrical accessories

can interfere with ignition or ECM/PCM power circuits.

If the problem began after an electrical modification, inspect that installation carefully.

Can P068A Return After Clearing the Code?

Yes.

If the underlying power-supply problem remains, the ECM/PCM can detect the abnormal shutdown again.

Clearing the code only removes the stored diagnostic information.

Should You Replace the ECM/PCM for P068A?

Usually, no—not based on the code alone.

P068A is often related to the power supply, relay, wiring, ignition circuit or voltage stability rather than a failed ECM/PCM.

Replacing the ECM/PCM without testing the power circuit can be expensive and may not solve the problem.

Common Diagnostic Mistakes With P068A

Replacing the ECM/PCM immediately

The power relay and power supply should be tested first.

Replacing the battery without testing it

A battery should be properly tested rather than replaced simply because P068A is present.

Replacing the relay without checking the socket

A damaged relay socket can cause the same problem with a new relay.

Ignoring grounds

Poor grounds can create unusual electronic symptoms and multiple diagnostic codes.

Checking only voltage with the ignition on

P068A concerns the behavior of the power supply during shutdown, so the key-off period is especially important.

Ignoring intermittent voltage drops

A brief interruption may be enough to set the code.

Ignoring other diagnostic codes

Communication and low-voltage codes can provide valuable clues.

Assuming the code always indicates a mechanical relay

Some modern vehicles use electronic power-management circuits rather than a simple conventional relay.

What Is the Correct Repair for P068A?

The correct repair depends on the confirmed cause.

Possible repairs include:

• Replacing the ECM/PCM power relay

• Repairing a damaged relay socket

• Repairing power-supply wiring

• Repairing an ignition-control circuit

• Cleaning or replacing corroded terminals

• Repairing battery connections

• Repairing engine or chassis grounds

• Replacing a weak battery

• Repairing the charging system

• Repairing a damaged fuse/relay box

• Removing or correcting an aftermarket electrical modification

• Updating ECM/PCM software

• Replacing the ECM/PCM only when an internal fault is confirmed

How to Test the Vehicle After Repair

After the repair, verify the ECM/PCM power supply under multiple conditions.

Check:

• Battery voltage

• Charging voltage

• ECM/PCM power voltage

• Relay operation

• Relay control signal

• Ignition signal

• Ground voltage drop

• ECM/PCM communication

• Key-off shutdown behavior

Then clear the diagnostic codes and perform several ignition cycles.

The vehicle should be monitored to confirm that the ECM/PCM remains powered for the correct shutdown period and that P068A does not return.

Frequently Asked Questions About P068A

What does P068A mean?

P068A means the ECM/PCM power relay de-energized earlier than expected.

Does P068A mean the ECM/PCM is bad?

No. The relay, battery, charging system, wiring, ignition circuit or grounds can cause the problem.

Can P068A cause a no-start?

Yes, if the ECM/PCM loses its required power supply.

Can P068A cause stalling?

Yes. An interruption in ECM/PCM power can cause the engine to stall.

Can a weak battery cause P068A?

Yes.

Can a bad alternator cause P068A?

Yes, indirectly through unstable or insufficient system voltage.

Can a bad relay cause P068A?

Yes. The ECM/PCM power relay is an important component to test.

Can a bad ground cause P068A?

Yes.

Can a loose battery terminal cause P068A?

Yes. A poor battery connection can cause intermittent power interruptions.

Can an ignition-switch problem cause P068A?

Yes, depending on the vehicle's electrical architecture.

Can P068A cause multiple unrelated codes?

Yes. A brief ECM/PCM power interruption can generate additional communication or sensor-related codes.

Can I drive with P068A?

If the vehicle runs normally, it may still be possible to drive it to a repair facility. However, if the vehicle is stalling, experiencing intermittent no-start conditions or losing electrical power while driving, continued driving is not recommended.

Should I replace the ECM/PCM because of P068A?

No. The power relay, battery, charging system, wiring, grounds and ignition circuit should be tested first.

Final Thoughts on P068A

P068A – ECM/PCM Power Relay De-Energized Performance – Too Early indicates that the ECM/PCM detected that its power relay shut down sooner than expected.

The most important point is that this code does not automatically indicate an ECM/PCM failure.

The problem can be caused by:

• Weak battery

• Charging-system problems

• Faulty ECM/PCM power relay

• Poor relay contacts

• Damaged relay socket

• Ignition-switch problems

• Damaged wiring

• Poor grounds

• Fuse-box problems

• Aftermarket electrical modifications

• Software issues

• ECM/PCM internal failure

A logical diagnostic sequence is:

Scan All Modules → Test Battery → Check Charging System → Inspect Battery Connections → Test ECM/PCM Power Relay → Inspect Relay Socket → Check ECM/PCM Power and Grounds → Monitor Power During Shutdown → Check Relay Control Signal → Check Ignition Circuit → Inspect Wiring → Check CAN Communication → Check Software → Evaluate ECM/PCM

Because P068A concerns the power supply of the engine control module, the relay and its electrical circuit should be thoroughly tested before replacing expensive electronic components.