Powertrain, generic (extended)

P2649 "A" Rocker Arm Actuator Control Circuit High (Bank 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The counterpart to P2648: the control circuit of rocker arm actuator A on bank 1 reads high, which means a short to battery voltage or a driver that cannot pull the line down. In GM's 2015 table 15OBDG05 the check needs the output driver commanded on, ignition in crank or run and supply above 11 V; 100 failures in 120 samples set a Type A fault. The Honda V6 (L66) in GM's 2004 table looks at the opposite situation: with the VTEC solenoid commanded off, a return signal at 12 V lasting 2 s points to a high circuit. A harness shorted to a power feed or an internal controller fault are the usual suspects; the actuator can then stay energised or be shut down by the controller.

Likely causes

Control wire shorted to a battery or ignition feed
Output driver in the engine controller no longer switches
Open ground side of the solenoid circuit

Symptoms

  • MIL on immediately
  • Lift switching disabled or permanently active
  • Rough running at idle if the actuator stays energised

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–600
Time0.5–2.5 h

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

Parts involved

rocker arm actuator a b1oil control valvewiring harness

Related codes

P2645P2648P2659P2654

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu.