The fault code P2646 usually indicates a low engine performance. This is a generic OBD-II fault code that can be used by many different makes and models. Some vehicles, like the Honda Civic, have a Variable Valves Timing and Lift Electronic Control System. This system controls the valve timing at all engine speeds to ensure that the engine is running as efficiently as possible. It allows for low fuel usage at low revs, while still delivering high performance at higher revs.
You need to know the functions of the camshafts and rocker arms before you can understand what this fault code could mean.
The valves are opened and closed to let air enter and leave the cylinders. The valve timing is set according to the position and size of the pistons. The camshafts are driven by the crankshaft using a timing chain or belt. Camshafts press on rocker arms. The rocker arms open or close exhaust or intake vales. Air can enter and leave the cylinders.
The engine control module (ECM/ECU), commands the rocker actuator (rocker pressure switch) to regulate the oil hydraulic circuit. Engine oil is pumped from the rocker to the VTEC System in order to adjust the engine valve timing. VTEC is used to increase engine performance, fuel efficiency or emissions. The ECM will generate fault code P2646 if it detects an issue with the rocker actuator.
The fault code P2646 indicates that the rocker arm actuator for Bank 1 is not working properly, or it is stuck in “Closed“. The letter “A”, refers the intake camshaft. Bank 1 is the side of the motor with the cylinder number 1 on it.
Table of Contents
What are the causes of fault code P2646?
- Low oil pressure that does not meet specifications
- Engine oil with incorrect viscosity (too thick or too thin)
- Blockage of oil channels
- Camshaft oil sensor malfunction (VTEC)
- Camshaft Oil Control Solenoid (VTEC)
- Connector and wiring issues
- ECM software that is outdated
What are the symptoms of fault code P2646?
- Engine fault lamp illuminates
- Reduced engine performance
- High fuel consumption
- The valves operate too loudly if the rocker arms are stuck
- Inconsistent acceleration
How to Fix Error Code P2646?
The oil in the engine is a common cause of this fault code. You must change the oil before replacing any part. This is usually the solution to the problem. Repairs and diagnosis that are incorrect can cause damage to your vehicle and cost money.
- – Check the engine oil viscosity. If it is incorrect or the oil has degraded then the filter and oil should be replaced.
- Check the engine for oil sludge. The channels should be flushed if necessary and synthetic oil used.
- Test the ‘A” rocker arm actuator and replace it if needed.
- Cables and connectors that lead to the actuator must be checked, repaired or replaced as necessary.
- After the system is repaired, it’s important to clear the fault codes.
How Serious is Fault Code P2646?
The P2646 fault code is not a life-threatening hazard but should be corrected as soon as you can because it will affect the engine’s performance. The P2646 code is not a very common fault code. It is not a common code but it can be seen on some makes and models of vehicles. Not all engine systems have rocker arms or actuators.
Remarks Concerning this Fault
Honda released a service bulletin on 16 July 2013 for the following Honda models:
- SB-10052884-2696:2003-2012 Honda Accord L4
- Honda Civic Si 2002-2005
- 2002-2009 Honda CR-V
- 2011 Honda CR-Z
- 2003-2011 Honda Element
- 2007-2011 Honda Fit
Bulletin addressed the P2646 fault code that was seen on the above vehicles. The issue is resolved by replacing the VTEC Oil Pressure Switch (Actuator) (P/N 37251-PNE-G01 H/C 6737217).
