Acura VCM Issues

March 30, 2020

This bulletin applies to 2014-2016 Acura NDX, 2013-2016 RDX, 2014-2016 RLX, 2014 RLX Sport Hybrid and 2016 RLX Sport Hybrid vehicles. While driving under steady cruise between 30 and 65 mph, or during light acceleration, the engine may intermittently run rough with the MIL blinking.

Since these driving conditions are likely to activate VCM operation, the probable reason for these symptoms is sticking VCM rocker arms.

If the engine rattles going into VCM, what you’re hearing is the VCM rocker arm pin tapping against the other rocker arm as it tries to lock the two arms together going into valve pause. If the engine runs rough with the MIL blinking, the VCM rocker arm pin can also stick in its locked position, causing both rocker arms to stay connected. When this happens, the engine intermittently runs rough and the MIL blinks.

If the engine is shut off and then restarted when either of these symptoms occur, the rocker arms may unstick, allowing normal operation with no misfire DTCs being set, which can make this problem tough to troubleshoot. To help you out, be sure to check out the Variable Cylinder management Rocker Arm test in the service manual. Replacing the affected rocker arm(s) usually fixes the problem.