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DTC codes / P06xx · Computer and output circuits / P068A

P068AECM/PCM Power Relay De-Energized Performance Too Early

P068A indicates that the engine control module (ECM) or powertrain control module (PCM) detected its main power relay de-energized earlier than expected during the shutdown sequence. The computer monitors the relay control circuit and power feed, and it sets this code when the relay drops out before the ECM has finished its controlled power-down routine, which can interrupt memory saving and cause hard starts or no-starts.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • Illuminated check engine light, often with no other noticeable symptoms
  • Intermittent no-start or hard start, especially after the engine has been shut off hot
  • Engine may stall immediately after startup or run rough for a few seconds
  • Loss of adaptive memory, causing poor driveability or transmission shift quality until relearned
  • Accessory power or dashboard lights that stay on or flicker after the key is turned off
  • Multiple unrelated communication or low-voltage codes stored alongside P068A

Common causes, most likely first

  1. Failing ECM/PCM power relay (main relay) with pitted or sticking contacts
  2. Corroded, loose, or damaged relay socket terminals or wiring in the relay control circuit
  3. Poor ground connection at the relay, ECM, or battery negative cable
  4. Weak or failing battery with low cranking voltage or a bad cell
  5. Faulty ignition switch or push-button start circuit that drops power to the relay control coil
  6. Damaged or chafed harness between the ECM and the relay, causing intermittent control voltage
  7. Internal ECM/PCM fault in the relay driver circuit (rare but possible)

How to diagnose and fix it

  1. Perform a battery and charging system test, including a load test and voltage drop check on both battery cables
  2. Inspect the ECM/PCM power relay and its socket for corrosion, burning, or loose terminals, and swap the relay with an identical known-good one if available
  3. Check for stored communication codes and freeze-frame data to see whether the fault occurs during shutdown or startup
  4. Backprobe the relay control circuit at the ECM connector and monitor voltage while cycling the key to confirm the ECM is commanding the relay correctly
  5. Measure voltage drop across the relay power and ground circuits under load to identify high-resistance connections
  6. If the relay and circuits test good, perform a wiggle test on the harness while monitoring relay control voltage to expose intermittent faults
  7. Replace the ECM/PCM only after all wiring, relay, and power supply checks have passed and the fault is proven internal to the module

Relay and ground checks before module replacement

  • A weak battery is a frequent hidden cause because the ECM may see the relay drop out during cranking voltage dips, so always load-test the battery before condemning the relay.
  • The relay can test fine on a bench but fail hot or under vibration, so a swap with a known-good relay is a faster diagnostic step than static resistance checks.
  • P068A often appears with U-codes or low-voltage codes because the early relay dropout cuts power to multiple modules, and those companion codes can mislead you toward a communication fault.
  • Corrosion inside the underhood fuse box or relay socket is commonly missed, especially on vehicles with a history of water intrusion or road salt exposure.
  • Do not replace the ECM/PCM based on this code alone; the relay driver circuit inside the module is rarely the culprit, and a replacement module will set the same code if the external circuit is still faulty.

Can I keep driving with P068A?

The vehicle may start and run normally, but the intermittent no-start or stall risk means you should avoid long trips and busy intersections until the fault is repaired. If the engine stalls or fails to restart, pull to a safe location and have the vehicle towed rather than repeatedly cranking.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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