P2646: Variable valve rocker arm not working as commanded (bank 1)
A rocker arm actuator system performance or stuck off, bank 1 (VTEC / VVL)
Severity: Inspect soon
The variable valve lift system is not engaging as commanded, usually because of oil pressure, oil quality or a switch or solenoid problem. Kelley Blue Book rates it critical and advises prompt inspection and not driving long distances.
It gets more serious if:
- Stop: Stop if the oil pressure light comes on, or the engine knocks, ticks loudly or loses power.
P2646 in short
P2646 means the bank 1 variable valve rocker arm system is not switching as the computer commands. Low or dirty oil, an oil pressure switch, or a solenoid or wiring fault are the usual causes. Some Toyotas have a software fix. Get it checked promptly and avoid long drives.
Honda VTEC and Toyota Valvematic style systems use oil pressure and an electric solenoid to change the valve lift. The computer sets P2646 when the system does not perform as commanded or is stuck off.
Low or dirty oil, the wrong viscosity, sludge, a failing oil pressure switch, a solenoid or its wiring can all prevent the change.
Honda has a bulletin saying the rocker arm oil pressure switch may fail intermittently and need replacing, for cars with P2646 or P2651 and related codes. Toyota revised the engine computer calibration on the 2014 Corolla with the 2ZR-FAE for P2646 and P265B.
Most likely causes
Cause 1: Low, dirty or wrong-viscosity oil, or sludge
Common general cause- Why it ranks here
- KBB lists low or dirty oil, wrong viscosity and sludge among the main causes.
- What would change this
- Rises if the oil is low, old or the wrong grade. Falls if the oil is fresh and correct.
Cause 2: Rocker arm oil pressure switch failing (Honda)
Supported by vehicle data- Why it ranks here
- Honda A13-021 says the rocker arm oil pressure switch may fail intermittently and need replacing on cars with P2646 or related codes. Only the NHTSA summary was read.
- What would change this
- Rises on an Element or Civic Si with intermittent codes. Falls if the switch tests normal.
Cause 3: Rocker arm control solenoid or wiring fault
Common general cause- Why it ranks here
- KBB lists the rocker arm control solenoids and wiring or corrosion.
- What would change this
- Rises if the solenoid or connector is damaged. Falls if it tests normal.
Cause 4: Engine computer calibration (2014 Corolla 2ZR-FAE)
Supported by vehicle data- Why it ranks here
- Toyota T-SB-0011-14 says the engine computer calibration was revised for P2646 and/or P265B. Only the NHTSA summary was read.
- What would change this
- Rises on an affected Corolla with the latest software not installed. Falls on other vehicles.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Check the oil level, condition and grade with the engine off and level.
IfThe oil is low, dirty or the wrong grade
It meansCorrect it, clear the code and recheck.
IfThe oil is fine
It meansCheck for bulletins.
Step 2: Ask a dealer whether your VIN has a bulletin or software update for P2646. Honda and Toyota have issued them.
IfA Honda Element or Civic Si has intermittent codes
It meansHonda says the oil pressure switch may need replacing.
IfA 2014 Corolla 2ZR-FAE needs the revised calibration
It meansUpdate the engine computer.
Points to: Engine computer calibration (2014 Corolla 2ZR-FAE)
IfNo bulletin applies
It meansHave the solenoid, switch and wiring tested.
Step 3: Have a shop test the rocker arm solenoid, oil pressure switch and wiring, and check the oil passages.
Warning:The parts are on the engine and tied to the oil system. Let a shop do it.
IfA solenoid or connector fault is found
It meansRepair or replace it.
IfThe switch is faulty
It meansReplace the oil pressure switch.
Symptoms
- Check engine light on
- Reduced power or poor fuel economy
- Unusual engine noise Gets more serious: stop and have it checked.
- Oil pressure warning light Gets more serious: stop and have it checked.
How to fix
Step 1: With the engine off and level, check the oil level and top up with the grade your manual specifies.
Step 2: Ask a dealer whether your VIN has a bulletin or software update for P2646.
On your vehicle
HondaYour car
2005–2010 · Element
Supported by vehicle dataHonda A13-021 says the rocker arm oil pressure switch may need replacing for P2646 and related codes. Whether it is still current is not verified.
2004 · CR-V
Supported by vehicle dataHonda bulletin 205 names P2646 with P2647, P2649 and P1009 on the 2004 CR-V. Whether the bulletin is still current is not verified.
A13-021Status unverified
MIL with P2646/P2651 or P2647/P2652 (rocker arm oil pressure switch)
2005–2010element · NHTSA 10098946
The rocker arm oil pressure switch may fail intermittently and need replacing; Civic Si also listed.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
205Status unverified
DTC P2646, P2647, P2649 or P1009
2004cr-v · NHTSA 10015291
The NHTSA summary does not give the repair.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
01-01-03Status unverified
DTCs P2646, P2648 service manual fix
2003accord · NHTSA 10001796
Service manual fix; the summary does not give the steps.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
ToyotaYour car
2014 · Corolla
Supported by vehicle dataToyota T-SB-0011-14 revises the engine computer calibration on 2014 Corollas with the 2ZR-FAE for P2646 and/or P265B. Whether it is still current is not verified.
2018–2019 · C-HR
Supported by vehicle dataToyota T-SB-0098-19 covers P2646 and Valvematic angle codes on the C-HR with the 3ZR-FAE engine. Whether the bulletin is still current is not verified.
T-SB-0011-14Status unverified
MIL with P2646 and/or P265B
2014corolla · NHTSA 10131906
The engine computer calibration was revised for the 2ZR-FAE engine.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
T-SB-0098-19Status unverified
MIL on with P2646, P265B, P10A0 or P1055 (Valvematic)
2018–2020c-hr, corolla · NHTSA 10164873
Follow the bulletin repair procedure for 2018-2019 C-HR and 2020 Corolla.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
No curated relationships for P2646 yet.
P2646 questions
Can I drive with P2646?
Kelley Blue Book rates it critical and advises prompt inspection and avoiding extended driving. Stop if the oil pressure light comes on or the engine knocks.
Is P2646 only a Honda code?
No. The title is generic, and bulletins exist for both Honda and Toyota variable valve lift systems.
Sources and review
- P2646 code: A rocker arm actuator system performance or stuck off, bank 1
- A13-021: MIL with P2646/P2651 or P2647/P2652 (rocker arm oil pressure switch)
- T-SB-0011-14: MIL with P2646 and/or P265B
- T-SB-0098-19: MIL on with P2646, P265B, P10A0 or P1055 (Valvematic)
- 205: DTC P2646, P2647, P2649 or P1009
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error