P0685 Acura Code - Engine Control Module Power Relay Control Circuit Open
Quick Answer
After the ignition switch is turned to LOCK (0) or the engine start/stop button is pressed to select the OFF mode, the Powertrain Control Module (PCM) does not shut down immediately. Common causes include Faulty Powertrain Control Module (PCM) Power Relay (PGM-FI Main Relay 1), Powertrain Control Module Power Relay harness is open or shorted, Powertrain Control Module Power Relay circuit poor electrical connection. 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 Powertrain Control Module (PCM) Power Relay (PGM-FI Main Relay 1), Powertrain Control Module Power Relay harness is open or shorted, Powertrain Control Module Power Relay circuit poor electrical connection.
- 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.
Code P0685 Acura Description
request of each device and system, the power supply is automatically disconnected (self-shutdown function). The PCM power is disconnected by controlling PGM-FI Main Relay 1. During a normal PCM shutdown, the shutdown process is executed by the CPU, PGM-FI Main Relay 1 is turned off, and the voltage to the PCM is turned off to shut down the PCM. When the voltage to the PCM is turned off and the PCM shuts down without the normal shutdown procedure, the PCM detects a malfunction in the PGM-FI main relay 1 control circuit and stores a Diagnostic Trouble Code (DTC).
What are the Possible Causes of the DTC P0685 Acura?
- Faulty Powertrain Control Module (PCM) Power Relay (PGM-FI Main Relay 1)
- Powertrain Control Module Power Relay harness is open or shorted
- Powertrain Control Module Power Relay circuit poor electrical connection
- Blown Powertrain Control Module fuse
- Faulty Powertrain Control Module
How to Fix the DTC P0685 Acura?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0685 Acura code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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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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