Powertrain, generic (extended)

P264A "A" Rocker Arm Actuator Position Sensor Circuit (Bank 1)

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

Some valve lift systems report back where the rocker arm actuator actually is, rather than relying on oil pressure; continuously variable designs driven by an electric motor, such as Toyota Valvematic, work this way. P264A is the general circuit fault for the position sensor of actuator A on bank 1: signal missing or implausible without a clear low or high pattern. No manufacturer documents this code publicly with thresholds; Toyota's Valvematic bulletin T-SB-0098-19 files its sensor fault under the B sensor code P265B. CARB demands monitoring of all electrical parts of such systems. Without valid feedback the controller usually freezes lift at a safe value, costing power and fuel economy.

Likely causes

Loose or corroded position sensor connector

Damaged signal, supply or ground wire

Position sensor failed internally

Symptoms

MIL on
Lift held at a fixed value, less power
Higher fuel consumption

Repair estimate

DifficultyHardWorkshop job

Parts and labour€100–700

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

rocker arm position sensor a b1wiring harness

References: law.cornell.edu, static.nhtsa.gov, en.wikipedia.org.