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P0685 Chevrolet Code - Engine Control Module Power Relay Control Circuit Open

Quick Answer

The P0685 code for Chevrolet vehicles indicates a problem with the engine control module (ECM) power relay control circuit being open. Common causes include Faulty engine control module power relay, Damaged or corroded wiring in the power relay circuit, ECM software or hardware issues. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0685 Chevrolet indicates Engine Control Module Power Relay Control Circuit Open.
Common causes
Common causes include Faulty engine control module power relay, Damaged or corroded wiring in the power relay circuit, ECM software or hardware issues.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 08, 2024
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Code P0685 Chevrolet Description

The P0685 code for Chevrolet vehicles indicates a problem with the engine control module (ECM) power relay control circuit being open. This means that the ECM is not receiving the necessary power signal from the relay, which can lead to various issues with engine performance and overall vehicle operation. The ECM plays a crucial role in managing the engine's functions, such as fuel injection, ignition timing, and emissions control. When the power relay control circuit is open, the ECM may not be able to function properly, leading to poor engine performance, reduced fuel efficiency, and potential stalling or failure to start.

OBDII Code P0685 Chevrolet - Engine Control Module Power Relay Control Circuit Open
P0685 Chevrolet Code - Engine Control Module Power Relay Control Circuit Open

Common Causes of P0685 Chevrolet

  1. Faulty engine control module power relay
  2. Damaged or corroded wiring in the power relay circuit
  3. ECM software or hardware issues
  4. Poor electrical connections or loose wires
  5. Battery or charging system problems

Symptoms of P0685 Chevrolet

  1. Engine misfires or hesitation during acceleration
  2. Engine stalling or difficulty starting
  3. Reduced fuel efficiency
  4. Illumination of the Check Engine Light
  5. Loss of power while driving

How to Fix P0685 Chevrolet

  1. Diagnose the issue by using a scan tool to retrieve the trouble code and check the power relay and wiring connections.
  2. Inspect the engine control module power relay for any signs of damage or malfunction. Replace if necessary.
  3. Check the wiring harness for any damage, corrosion, or loose connections. Repair or replace as needed.
  4. Clear the trouble code and reset the ECM to see if the issue has been resolved.
  5. Test drive the vehicle to ensure that the symptoms have been eliminated and the code does not return.

Cost to Fix P0685 Chevrolet

The cost of repairing a P0685 code on a Chevrolet vehicle can vary depending on the specific cause of the issue and the labor rates in your area. On average, the repair cost for this problem can range from $100 to $300, including parts and labor. Keep in mind that additional diagnostic time may be needed to pinpoint the exact cause of the problem, so it's essential to consult with a professional mechanic for an accurate estimate. Labor rates at auto repair shops typically range from $80 to $150 per hour, but this can vary based on location and shop rates.

What does this mean?

Tech Notes for P0685 Chevrolet

Check all the Engine Control Module (ECM) fuses, if the fuses are OK, then replacing the ECM relay should take care of the problem.

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Information for Specific Chevrolet Models

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0685 Chevrolet Code

1. What are the common symptoms of OBDII code P0685 in a Chevrolet vehicle?

- Common symptoms include engine stalling, difficulty starting the engine, poor engine performance, and illuminated Check Engine Light.

2. What does the OBDII code P0685 on a Chevrolet indicate?

- The code P0685 indicates a problem with the Engine Control Module Power Relay Control Circuit being open.

3. What are the possible causes of the OBDII code P0685 in a Chevrolet?

- Possible causes include a faulty engine control module relay, damaged wiring or connectors in the relay circuit, or a malfunctioning engine control module.

4. How can I diagnose the cause of OBDII code P0685 in my Chevrolet?

- You can start by checking the engine control module relay for proper operation, inspecting the wiring and connectors for any damage, and testing the engine control module for faults using a diagnostic scanner.

5. Can I still drive my Chevrolet with OBDII code P0685?

- It is not recommended to drive your vehicle with code P0685 as it can lead to engine performance issues and potential stalling, which can compromise safety.

6. How can I repair OBDII code P0685 in my Chevrolet?

- Repair methods may include replacing the faulty engine control module relay, repairing damaged wiring or connectors, or replacing the engine control module if necessary.

7. Are there any DIY tips for troubleshooting OBDII code P0685 in a Chevrolet?

- You can start by checking the relay and its connections for any obvious signs of damage and ensuring they are securely connected. However, for a more accurate diagnosis, professional help may be needed.

8. Can a weak battery cause OBDII code P0685 to trigger in a Chevrolet?

- Yes, a weak or failing battery can sometimes cause voltage fluctuations that may trigger code P0685. It is recommended to check the battery's condition as part of the diagnostic process.

9. How long does it typically take to repair OBDII code P0685 in a Chevrolet?

- The repair time can vary depending on the exact cause of the code and the availability of parts. It can range from a quick relay replacement to a more involved repair involving the engine control module.

10. Will resetting the Check Engine Light make OBDII code P0685 go away?

- Resetting the Check Engine Light may temporarily turn it off, but if the underlying issue causing code P0685 is not addressed, the light is likely to come back on once the problem is detected again.

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