Powertrain, generic (extended)

P264C "A" Rocker Arm Actuator Position Sensor Circuit Low (Bank 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P264C is set when the signal from the position sensor of rocker arm actuator A, bank 1, sits below its valid window. Typical electrical explanations are a short of the signal wire to ground, a lost 5 V reference, or a sensor that has failed internally. CARB lists such out-of-range checks for every sensor in a lift or timing system under the comprehensive component rules. No carmaker publishes P264C with a threshold; it would only appear on engines whose actuator carries position feedback, such as motor-driven continuous lift designs. Expect the controller to stop adjusting lift, with weaker pull and higher consumption; P264D is the high-side counterpart.

Likely causes

Signal wire shorted to ground
5 V sensor supply missing
Position sensor failed internally

Symptoms

  • MIL on
  • Weaker pull, lift no longer varied
  • Higher fuel consumption

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–600
Time0.5–2.5 h

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

Parts involved

rocker arm position sensor a b1wiring harness

Related codes

P264AP264DP266CP265C

References: law.cornell.edu, en.wikipedia.org, en.wikipedia.org.