Engine-CodesAcura – P0685 Acura

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

Quick Answer

The P0685 code for Acura vehicles indicates that there is an issue with the Engine Control Module (ECM) Power Relay Control Circuit being open. Common causes include Faulty power relay, Loose or corroded electrical connections in the circuit, Wiring harness 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 Acura indicates Engine Control Module Power Relay Control Circuit Open.
Common causes
Common causes include Faulty power relay, Loose or corroded electrical connections in the circuit, Wiring harness 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.
Table of contents Created and updated by William Orellana on Aug 18, 2024
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Code P0685 Acura Description

The P0685 code for Acura vehicles indicates that there is an issue with the Engine Control Module (ECM) Power Relay Control Circuit being open. This means that there is a malfunction in the circuit that controls the power relay for the ECM, which can lead to a loss of communication between the ECM and other vital components of the vehicle. The ECM is responsible for managing various engine functions, such as fuel injection timing, ignition timing, and emissions control. When the power relay control circuit is open, it can result in poor engine performance, decreased fuel efficiency, and potential engine stalling.

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

Common Causes of P0685 Acura

  1. Faulty power relay
  2. Loose or corroded electrical connections in the circuit
  3. Wiring harness issues
  4. ECM malfunction
  5. Fuse related issues

Symptoms of P0685 Acura

  1. Engine stalling or rough idling
  2. Check Engine Light illuminated on the dashboard
  3. Difficulty starting the vehicle
  4. Poor fuel efficiency
  5. Loss of power while driving

How to Fix P0685 Acura

  1. Begin by diagnosing the exact cause of the P0685 code using a diagnostic scanner.
  2. Inspect the power relay and replace it if faulty.
  3. Check and tighten any loose or corroded electrical connections in the circuit.
  4. Inspect the wiring harness for any damage or wear and repair as needed.
  5. If the ECM is found to be faulty, it may need to be replaced.

Cost to Fix P0685 Acura

The typical cost to repair the P0685 code in an Acura vehicle can range from $100 to $300, depending on the specific cause of the issue and the cost of parts and labor in your area. It's important to note that diagnostic time and labor rates at auto repair shops can vary, so it's advisable to get quotes from multiple sources before proceeding with the repair.

Tech Notes for P0685 Acura

Check all the Powertrain Control Module (PCM) fuses, if the fuses are OK, then replacing the PCM Power Relay (also label as PGM-FI Main Relay 1) 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 Acura Code

1. What does the OBDII code P0685 mean on an Acura?

P0685 indicates an open circuit in the Engine Control Module (ECM) power relay control circuit, meaning the ECM may not be receiving proper power to function correctly.

2. What are the common symptoms of code P0685 on an Acura?

Symptoms may include engine stalling, failure to start, rough idling, and a lit check engine light.

3. What causes the P0685 code to appear on an Acura?

Common causes include a faulty ECM power relay, damaged wiring or connectors in the relay circuit, or a defective Engine Control Module (ECM).

4. Can I drive my Acura with the P0685 code active?

It's not recommended to drive with this code active, as it can lead to intermittent stalling or complete engine failure, potentially leaving you stranded.

5. How do I diagnose the P0685 code on an Acura?

Diagnosis involves checking the ECM power relay, inspecting the wiring and connectors in the control circuit for damage, and testing the ECM for proper functionality.

6. How can I fix the P0685 code on my Acura?

Repairs may include replacing a faulty ECM power relay, repairing or replacing damaged wiring or connectors, or, in rare cases, replacing the ECM.

7. How much does it cost to repair the P0685 code on an Acura?

Repair costs vary but typically range from $50 to $200 for parts and labor, depending on whether the relay, wiring, or ECM needs replacement.

8. Can a dead battery cause the P0685 code on an Acura?

A dead battery itself is unlikely to cause this code, but low voltage or electrical issues related to the battery could potentially affect the ECM power relay circuit.

9. Will clearing the P0685 code with a scanner fix the problem?

Clearing the code may temporarily reset the check engine light, but it won’t fix the underlying issue causing the open circuit in the ECM power relay control.

10. Do I need a professional mechanic to fix the P0685 code on my Acura?

While experienced DIYers may be able to handle basic repairs, seeking assistance from a professional mechanic is recommended for accurate diagnosis and repair, especially if ECM replacement is required.

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