OBD-II Error Code P0685 - Computer Output Circuit - Code 685

OBD-II Standard OBD-II Major Computer Output Circuit

Model: SAE J2012 Standard | Code: P0685

Applicable Systems
OBD-II

Symptoms

The check engine light illuminates. Various engine management functions may be affected. An ECM output circuit or actuator has a malfunction.

Possible Causes

  • Faulty ECM output driver circuit
  • Actuator or relay circuit open or shorted
  • Wiring harness damage to ECM output circuit
  • Corroded connector at ECM or actuator
  • Aftermarket accessory interfering with ECM circuit

Troubleshooting Steps

  1. Step 1: Connect an OBD-II scan tool and read all stored DTCs and freeze frame data
    All DTCs and freeze frame data are retrieved
  2. Step 2: Inspect the related wiring and connectors for the indicated system
    Wiring and connectors are in good condition
  3. Step 3: Use a digital multimeter to check sensor voltage, resistance, and continuity per manufacturer specifications
    Values are within specified range
  4. Step 4: Test the related actuator, sensor, or solenoid for proper operation
    Component operates within specification or fails definitively
  5. Step 5: Clear codes and perform a road test or drive cycle to verify repair
    Code does not return and system operates normally

How to Reset

To reset code P0685: 1) Repair the underlying fault. 2) Use an OBD-II scan tool to clear the DTC. 3) Perform a drive cycle to verify the monitor completes. 4) If the code returns, further diagnosis is needed. Caution: Do not clear codes without fixing the root cause.

Frequently Asked Questions

  • Q: What does OBD-II code P0685 mean?

    Code P0685 indicates: Computer Output Circuit - Code 685. This is a SAE J2012 standard diagnostic trouble code related to Computer Output Circuit.

  • Q: How serious is code P0685?

    Severity: Major. Immediate attention is recommended.

  • Q: Can I drive with code P0685?

    Not recommended - may cause further damage.

  • Q: How do I fix code P0685?

    Diagnose the Computer Output Circuit system, check wiring and connectors, test related components, and replace faulty parts as needed.

Related OBD-II Standard Fault Codes

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Source: SAE J2012 Standard - Powertrain Diagnostic Trouble Codes

Category: OBD-II