Network, generic

U011C Lost Communication With Rocker Arm Control Module B

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

U011C is the partner of U011B for rocker arm control module B, for example the controller of the second cylinder bank or of a second group of switchable rocker arms where the task is split across two units. The engine controller expects cyclic status from it, such as the confirmed lock state per cylinder, and records U011C once those frames fail to arrive. No manufacturer documents this code publicly, and it remains open which production engines use a separate B module at all; the entry relies on CARB's call for separate lack-of-communication codes and its monitoring rules for valve lift and control. Invalid data from this module is U041D. Without the B unit the affected cylinders usually stay in full-lift mode: MIL, possibly uneven running and more fuel.

Likely causes

Module B without power or ground
Contaminated or loose connector at the second cylinder head
Open or shorted CAN lines to module B
Rocker arm control module B internally faulty

Symptoms

  • MIL on
  • Affected cylinders remain in full-lift mode
  • Uneven running or higher consumption

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–1,200
Time1–4 h

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

Parts involved

rocker arm module bcan bus wiring

Related codes

U011BU041DU0100

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