P0685 on Nissan: How to Diagnose & Fix
ECM/PCM Power Relay Control Circuit/Open
3 Nissan models · 3 documented issues · 3 critical
P0685 on Nissan by model: symptoms, diagnosis and fix
A well-documented problem on 2002-2006 Altima involves failure of the engine control module (ECM) relay, which can interrupt power to the ECM while driving or prevent the car from starting. Owners report sudden stalling, intermittent crank-no-start, or an engine that dies and restarts after cooling down. Nissan issued a safety recall because relay heat damage and internal failure could cause an unexpected engine stall.
Common Symptoms
- engine stalls while driving
- intermittent no-start
- cranks but will not start
- engine restarts after sitting
- loss of power with warning lights illuminated
How to Fix
Confirm recall completion status by VIN first. Diagnosis typically includes checking for ECM power loss, relay operation, and signs of heat damage or intermittent contact in the IPDM/relay circuit. The fix is replacement of the ECM relay with the updated part per recall procedure; if symptoms persist, inspect related fuse box terminals and wiring for overheating or poor pin tension.
Nissan's 10V517000 recall reaches the 2005 and 2006 Frontier pickup. At issue is the ECM relay contained in the Frontier's Intelligent Power Distribution Module assembly. The relay's diode uses a silicon molding to reduce electrical current noise, but Nissan found the relay may allow silicon vapor to form; as silicon evaporates from that molding, arcing deposits silicon oxide on the relay contact. According to Nissan, this can cause the engine to stall — the reason the campaign was filed as a safety recall rather than a service bulletin. Note that the 747,480 units listed apply to the campaign as a whole, which spans several Nissan and Infiniti models.
Common Symptoms
- Engine stalling
How to Fix
Take the truck to a Nissan dealer, where the ECM relay inside the IPDM assembly is replaced free of charge. The recall began December 6, 2010. Before scheduling, enter your Frontier's VIN at nhtsa.gov/recalls — that will tell you whether the relay replacement is still outstanding on your specific truck. Nissan customer service: 1-800-647-7261.
Sources for this issue (1)
Nissan recall campaign 10V-517/PC068 exactly covers 2005-2006 Xterra. Oxidation on ECM-relay electrical contacts in the IPDM can interrupt ECM power, cause engine-performance problems and permit stalling at low engine speed. The campaign replaces the relay with a new one after VIN eligibility is confirmed. The frozen silicon-evaporation narrative is more specific than the campaign bulletin and is not needed to support this indexed identity.
Common Symptoms
- low-speed stall and ECM power interruption documented
- campaign eligibility checked by VIN
- relay, IPDM terminals, battery and grounds separated
How to Fix
Check Service COMM or Nissan recall status by VIN. If PC068 is open, have a Nissan dealer replace the ECM relay in the IPDM using the campaign procedure at no charge. For a completed or ineligible vehicle with a stall, preserve power-loss data and test ECM power, relay control, IPDM terminals, battery and grounds before replacement. Do not buy a relay or IPDM from this page; campaign status and exact electrical diagnosis must be established first.
Sources for this issue (2)
P0685 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0685 mean on a Nissan?
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. On Nissan it is documented across 3 models: Altima, Frontier, Xterra.
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 on a Nissan?
Repair costs vary widely with the root cause and Nissan model; each issue on this page carries its own estimate where one is published.
Looking for P0685 on a different make?
View P0685 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.