What Does P068B Mean?
The PCM has detected that the ECM/PCM power relay de-energized too late during the key-off sequence. The relay is remaining engaged longer than the programmed shutdown window. This keeps the PCM powered beyond its expected shutdown time, which can drain the battery or prevent the vehicle from fully powering down. The driver may notice parasitic battery drain or the engine running longer than expected after key-off.
Common Causes
35%
ECM/PCM power relay contacts welded or sticking closed
25%
PCM not releasing the relay control signal due to software hang
20%
Short to voltage on the relay control circuit holding the coil energized
10%
Ignition switch not fully transitioning to off position
10%
Body control module or accessory keeping the PCM awake signal active
Diagnostic Steps
1
Monitor the relay de-energization time with a voltmeter on the relay output during key-off; note how long it takes to drop to 0V and compare to the manufacturer's specification.
2
Check if the relay physically clicks off when it should by listening or feeling the relay during key-off; stuck contacts will not produce a click.
3
Remove the relay and check if the contacts spring open freely; measure contact resistance in the off state (should be OL/infinite).
4
Monitor the PCM relay control circuit voltage during and after key-off; it should drop to 0V within the programmed shutdown time. A maintained voltage indicates the PCM is not releasing the relay.
5
Check for parasitic draw with an ammeter; current draw above 50mA after 30 minutes with the key off confirms the relay is holding the PCM powered.
Estimated Repair Cost
$75 - $600
Parts + labor, varies by vehicle and location
The PCM has detected that the ECM/PCM power relay de-energized too late during the key-off sequence. The relay is remaining engaged longer than the programmed shutdown window. This keeps the PCM powered beyond its expected shutdown time, which can drain the battery or prevent the vehicle from fully ...
The most common cause of P068B (ECM/PCM Power Relay De-Energized Performance - Too Late) is: ECM/PCM power relay contacts welded or sticking closed
Typical repair costs for P068B range from $75 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The primary risk is parasitic battery drain, which can leave the driver stranded with a dead battery. If the relay contacts are welded closed, the PCM remains powered indefinitely, draining the battery overnight. Repair to prevent dead battery situations.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P068B to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Control Module Power Supply
Difficulty
Type
Generic (SAE)
Recommended Tools
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