Engine-CodesVolkswagen – P0685 Volkswagen

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

Quick Answer

The P0685 code for Volkswagen vehicles indicates a problem with the Engine Control Module (ECM) power relay control circuit being open. Common causes include Faulty ECM power relay, Wiring issues such as a short circuit or open circuit, Defective ECM. 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 Volkswagen indicates Engine Control Module Power Relay Control Circuit Open.
Common causes
Common causes include Faulty ECM power relay, Wiring issues such as a short circuit or open circuit, Defective ECM.
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.
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P0685 Volkswagen Description

The P0685 code for Volkswagen vehicles indicates a problem with the Engine Control Module (ECM) power relay control circuit being open. In simpler terms, this means that the ECM is not receiving the necessary power to function properly. The ECM is a critical component of the vehicle's onboard computer system, responsible for controlling various engine functions such as fuel injection, ignition timing, and emissions. When the power relay control circuit is open, it can lead to a range of issues that can impact the vehicle's overall performance, efficiency, and drivability.

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

Common Causes of P0685 Volkswagen

  1. Faulty ECM power relay
  2. Wiring issues such as a short circuit or open circuit
  3. Defective ECM
  4. Corrosion or poor connections in the relay control circuit
  5. Electrical system malfunctions

Symptoms of P0685 Volkswagen

  1. Check Engine Light illuminated on the dashboard
  2. Engine misfires or runs rough
  3. Decreased fuel efficiency
  4. Vehicle may stall or have trouble starting
  5. Loss of power or acceleration

How to Fix P0685 Volkswagen

  1. Diagnose the issue by using a scan tool to read the fault codes and determine the exact cause of the problem.
  2. Inspect the wiring and connections in the ECM power relay control circuit for any damage or corrosion. Repair or replace as necessary.
  3. Test the ECM power relay to ensure it is functioning properly. Replace if faulty.
  4. Clear the fault codes and reset the ECM to see if the issue has been resolved.
  5. Test drive the vehicle to confirm that the problem has been fixed and that the Check Engine Light does not reappear.

Cost to Fix P0685 Volkswagen

The cost of repairing a P0685 code on a Volkswagen can vary depending on the specific cause of the issue and the labor rates at the auto repair shop. In general, you can expect to pay anywhere from $100 to $300 for parts and labor. Keep in mind that prices may be higher at dealerships or in metropolitan areas, while independent shops may offer more competitive rates. It's recommended to get a few quotes from different mechanics to ensure you are getting a fair price for the repair.

Tech Notes for P0685 Volkswagen

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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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 Volkswagen Code

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

- Common symptoms include engine stalling, difficulty starting the vehicle, and illuminated Check Engine light.

2. What does the OBDII code P0685 for a Volkswagen indicate?

- This code indicates a problem with the Engine Control Module (ECM) power relay control circuit being open or malfunctioning.

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

- Possible causes include a faulty ECM power relay, damaged wiring or connectors in the power relay circuit, or a defective ECM.

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

- You can diagnose the issue by checking the power relay and related wiring for any visible damage, testing the relay for proper functionality, and using a multimeter to check for continuity in the circuit.

5. Can I drive my Volkswagen with the P0685 code present?

- It is not recommended to drive your vehicle with the P0685 code present, as it can lead to performance issues and potential further damage to the engine control system.

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

- Repair options include replacing the ECM power relay, repairing damaged wiring or connectors, or replacing the Engine Control Module if necessary.

7. Is it possible to reset the P0685 code in a Volkswagen without fixing the underlying issue?

- While you can clear the code with an OBDII scanner, it will likely reappear until the root cause of the problem is addressed.

8. Can a DIY enthusiast fix the P0685 code in a Volkswagen?

- Depending on your skill level and access to tools, a DIY enthusiast may be able to diagnose and fix the issue, especially if it involves replacing a relay or repairing wiring.

9. Will the P0685 code cause any long-term damage to my Volkswagen?

- Ignoring the P0685 code can potentially lead to further damage to the engine control system, so it's best to address the issue promptly to prevent any long-term damage.

10. How much can I expect to pay to repair the P0685 code in my Volkswagen?

- The cost of repairing the P0685 code can vary depending on the specific cause of the issue, but it may range from $100 to $500 or more, including parts and labor.

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