Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0685: Pcm Power Control Circuit Malfunction
2004 Acura 3.5RLSECTION DTC P0685: Pcm Power Control Circuit Malfunction
WARNING: This page is about a different car, the 2003 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
When substituting or replacement of PCM is recommended, see PCM REMOVAL & REPLACEMENT
for important precautions.
- Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
- Wait 1 second.
- Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0685 is set, update the PCM if it does not have the latest software, or substitute a known-good PCM. If the problem goes away with a known-good PCM, replace PCM. If DTC P0685 is not set, problem is intermittent, system is OK at this time.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.