Code result
P2646
A Rocker Arm Actuator System Performance/Stuck Off Bank 1
Moderate severity
What it means
The rocker arm actuator A on bank 1 is commanded to engage (high lift or all-cylinder mode) but does not switch. Engine stays in low-lift or deactivated mode under load, causing reduced power.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Low oil pressure cannot move the actuator
highOne of the most commonly reported causes for this code — check this first.
Mechanical lock pin stuck in unactivated position
mediumA plausible cause — test and verify before replacing parts.
Carbon or debris buildup preventing free movement
lowLess common, but worth ruling out after the more likely causes.
Related help
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