OBD-II code family
Rocker Arm Oil Pressure Switch Circuit Faults (2 codes)
2 related fault descriptions. Use each full code and the exact vehicle service information to identify its circuit, monitored condition, and required tests.
Codes in this family
This is the complete published member list for this guide. Each code retains its own page; shared diagnostic context does not mean that every member has the same test or repair.
What these codes mean
These pages cover Honda’s P2646 low-voltage and P2647 high-voltage rocker arm oil pressure switch descriptions in Service Bulletin 13-021, Version 3, dated September 16, 2015. The bulletin also groups P2651 with P2646 and P2652 with P2647; those pairings belong to its listed Honda applications. A matching code number on another make can have different service wording. For example, Toyota’s May 2015 revision for the 2014 Corolla with the 2ZR-FAE engine describes P2646 as an actuator-system performance or stuck-off condition. Match the complete scan report to the actual vehicle before choosing a procedure.
In the Honda bulletin, low and high describe the switch-circuit voltage labels. They are not oil-pressure measurements and do not establish that oil pressure is normal. The two labels also do not, on their own, identify a short, an open connection or a failed switch. A technician needs the applicable wiring and diagnostic information to distinguish those possibilities.
Honda identifies intermittent switch failure as a possible cause and specifies replacement of the switch and its O-ring for the described condition. It warns that the symptom may be absent after clearing the code. Save diagnostic information before clearing; an intermittent or currently absent symptom does not establish a completed repair. If the code returns after the bulletin repair, Honda directs the technician to troubleshoot the particular code rather than repeat the replacement without diagnosis.
Keep electrical and oil-system tests with a qualified technician. An owner can record warnings and symptoms and arrange inspection; do not bypass the switch or work around a running engine. An oil-pressure warning, new engine noise or serious power loss calls for stopping safely and arranging assistance. Ask for an itemized estimate based on the confirmed fault, including diagnosis, required parts and seals, and verification, rather than choosing a solenoid, control-valve assembly or switch solely from the code label.
Identify the circuit on your vehicle
Match the full DTC, reporting module, and any failure-type suffix to the service information for your exact year, make, model, engine, and equipment. An identifier alone does not establish installed hardware count, location, connector pinout, or a universal measurement.
Where the manufacturer publishes its own meaning for this code, that is the one to work from — it describes the actual component on your vehicle, which the generic definition cannot. Keep the generic description for what it is good for: it tells you which subject area the standard assigned the code to, which is useful context when the two appear to disagree. If they do disagree, follow the manufacturer.