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

Quick Answer

The P0685 diagnostic trouble code (DTC) for Audi vehicles indicates a problem with the engine control module power relay control circuit being open. Common causes include Faulty engine control module power relay, Wiring or connection issues in the power relay control circuit, Corrosion or damage to the relay or related components. 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 Audi indicates Engine Control Module Power Relay Control Circuit Open.
Common causes
Common causes include Faulty engine control module power relay, Wiring or connection issues in the power relay control circuit, Corrosion or damage to the relay or related components.
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 Aug 19, 2024
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Code P0685 Audi Description

The P0685 diagnostic trouble code (DTC) for Audi vehicles indicates a problem with the engine control module power relay control circuit being open. This means that there is an issue with the relay that controls the power supply to the engine control module (ECM), which is a critical component responsible for managing various engine functions and ensuring proper performance. When this circuit is open, it can lead to a loss of power to the ECM, causing a range of performance issues and potentially impacting the vehicle's drivability.

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

Common Causes of P0685 Audi

  1. Faulty engine control module power relay
  2. Wiring or connection issues in the power relay control circuit
  3. Corrosion or damage to the relay or related components
  4. ECM software or hardware malfunction
  5. Electrical system issues affecting the power relay

Symptoms of P0685 Audi

  1. Engine stalling or not starting
  2. Decreased engine performance or rough idling
  3. Check engine light illuminated on the dashboard
  4. Difficulty accelerating or loss of power while driving
  5. Poor fuel efficiency

How to Fix P0685 Audi

  1. Begin by conducting a thorough visual inspection of the power relay and its connections to identify any visible damage or corrosion.
  2. Use a multimeter to test the power relay for proper functionality and continuity.
  3. Check the wiring and connections in the power relay control circuit for any breaks, shorts, or loose connections.
  4. Replace the faulty power relay if it fails testing or shows signs of damage.
  5. Clear the DTC from the vehicle's ECM memory and test drive the vehicle to confirm that the issue has been resolved.

Cost to Fix P0685 Audi

The typical cost to repair a P0685 code in an Audi can range from $150 to $300, including parts and labor. However, prices may vary depending on the specific model of the Audi, the location of the repair shop, and the extent of the issue. It is recommended to get a detailed quote from a reputable auto repair shop to determine the exact cost for resolving this problem.

What does this mean?

Tech Notes for P0685 Audi

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 Audi Code

1. What are the common symptoms of OBDII code P0685 in an Audi related to the Engine Control Module Power Relay Control Circuit Open?

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

2. What are the possible causes of OBDII code P0685 in an Audi?

- Possible causes include a faulty engine control module (ECM), a damaged power relay, loose or corroded electrical connections, or a wiring issue.

3. How can I diagnose the Engine Control Module Power Relay Control Circuit Open issue in my Audi?

- To diagnose P0685, it's recommended to perform a visual inspection of the power relay and associated wiring, check for loose connections, and use a multimeter to test the relay's functionality.

4. Can I drive my Audi with OBDII code P0685 present?

- It is not recommended to drive your Audi with code P0685 present, as it can lead to more severe issues like engine failure or electrical problems.

5. How can I repair OBDII code P0685 in my Audi?

- Repairing P0685 typically involves replacing a faulty power relay, repairing damaged wiring, or replacing the engine control module if necessary.

6. Are there any DIY tips for fixing OBDII code P0685 in my Audi?

- DIY tips include checking and cleaning electrical connections, inspecting and replacing damaged wiring, and ensuring the power relay is securely in place.

7. Is it necessary to reset the OBDII code P0685 after repairs are completed on my Audi?

- Yes, it is important to reset the code using an OBDII scanner after repairs to clear the fault code and turn off the check engine light.

8. Can a low battery voltage cause OBDII code P0685 to trigger in an Audi?

- Yes, low battery voltage can potentially cause code P0685 to trigger due to insufficient power supply to the engine control module and power relay.

9. What are the long-term effects of ignoring OBDII code P0685 in an Audi?

- Ignoring code P0685 can lead to more severe electrical issues, engine performance problems, and potential damage to other components in the vehicle.

10. Is it recommended to seek professional help for diagnosing and repairing OBDII code P0685 in my Audi?

- Yes, it is advisable to seek help from a qualified mechanic or dealership specializing in Audi vehicles for accurate diagnosis and proper repair of code P0685 to ensure safety and reliability.

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