P0685 on Honda Accord
ECM/PCM Power Relay Control Circuit/Open
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Honda Accord context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0685.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What P0685 Means on Your Honda Accord
P0685 is a diagnostic trouble code indicating: ECM/PCM Power Relay Control Circuit/Open. This code relates to the computer and output circuits system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real Honda Accord Owner Reports
Source: NHTSA Complaints Database
"First of all i'm really surprised to find out that honda does not have a recall for the a pcm - ecm power relay. this should be a safety issue. basically while driving my car if i have the heat on the vehicle will turn off when i slow down or come to a stop."
"Check engine light went on and off a few times, took it to autocheck and found a code. took it to dealer, they could not locate the code and claimed there is no issue they can find, come back when it happens again."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Honda Accord
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.