P0685: ECM/PCM Power Relay Control Circuit/Open
4 vehicles · 4 makes · $300-$1,500 repair
Most Reported On
P0685 is an OBD-II diagnostic trouble code meaning “ECM/PCM Power Relay Control Circuit/Open.” An open or general fault in the control circuit for the ECM/PCM main power relay. The module cannot properly control the relay that supplies its own switched power. This code is most commonly reported on 2015-2017 Mitsubishi Outlander, 2002-2006 Nissan Altima, and 2009-2013 Dodge Journey, plus 1 other vehicle, with repair costs ranging from $300 to $1,500.
Common Causes
Typical Repair Cost
Based on 4 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
This is a powertrain code, so a basic OBD-II reader can read it. These read P0685.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple code reader for engine (P) codes on many compatible OBD-II vehicles. It does not support every vehicle or hybrid/EV application, and it does NOT read body, chassis or network codes; confirm exact-vehicle compatibility before buying.
- Read & clear engine (P) codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth scanner with a companion app that reads beyond the engine module — ABS, SRS and transmission — plus manufacturer-specific codes on many vehicles.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X V3.0 Elite OBD-II Scanner
by LAUNCH
Handheld scanner covering the four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level tablet with all-system coverage and bi-directional control, so you can command a module rather than only read it.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
What you can do yourself, and what needs a shop
Reading the code, clearing it, and watching whether it returns is a driveway job with the right scanner. These steps are not:
- Module programming or software updates — needs the manufacturer software or a J2534 pass-through with a paid subscription.
- Replacing a control module — most are VIN-programmed and immobilizer-registered, so a new one does nothing until it is coded to your car.
- Airbag/SRS component work — a stored fault can deploy a live device.
If the vehicle is still under warranty, check for an open recall or technical service bulletin before buying anything — the repair may already be covered.
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Vehicles Affected (4)
FAQ
What does P0685 mean?
P0685 stands for "ECM/PCM Power Relay Control Circuit/Open." An open or general fault in the control circuit for the ECM/PCM main power relay. The module cannot properly control the relay that supplies its own switched power.
What are the most common causes of P0685?
The most common causes of P0685 are: Faulty ECM/PCM power relay, Open in the relay control circuit, Corroded/damaged connectors, Blown fuse, Internal PCM driver fault. The specific cause varies by vehicle.
How much does it cost to fix P0685?
Repair costs for P0685 range from $300 to $1,500, depending on the vehicle and root cause.
Which vehicles are affected by P0685?
Au7o has documented P0685 across 4 vehicle models from 4 manufacturers: Dodge, Mitsubishi, Nissan, RAM.
Sources (7)
- articleNHTSA Recall 17V609000 — Mitsubishi Outlander Electrical System: Relay
- articleNHTSA Recall Manufacturer Notice RCMN-17V609 (PDF)
- articleMitsubishi SR-17-005 — Electrical Power Control Relay Safety Recall Campaign, 2015-2017
- NHTSANHTSA Manufacturer Communications Data Corpus
- articleDodge Ram TIPM Failure Symptoms, Repair, and Replacement - Circuit Board Medics
- ForumMost Common Dodge RAM TIPM Problems - RamForum.com
- ForumTIPM Fuel Pump Failure, Repair & Subsequent Problems - RamForumZ
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.