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U041D Invalid Data Received From Rocker Arm Control Module B

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

U041D is the counterpart for rocker arm control module B, used where the switching of rocker arms is split, for instance by cylinder bank. The code tells that the engine controller still receives B's messages, but their lift or lock status cannot be trusted. Comparing with U041C helps: B alone points to that module, its harness branch or its solenoids, both together to the shared supply or the bus. No manufacturer documents U041D publicly and no thresholds are known. CARB requires monitoring of variable valve lift and plausibility checks of digital inputs. Likely effects: MIL, cylinders on the B side held in full-lift mode, higher fuel use and perhaps rough running. U011C is lost contact.

Likely causes

Switching solenoid or oil supply on the B side faulty
Rocker arm control module B internally faulty
Shared supply or bus fault (then usually with U041C)

Symptoms

  • Check engine light
  • Uneven running or higher fuel use

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,200
Time0.5–4 h

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

Parts involved

rocker arm module bcan bus wiring

Related codes

U011CU041CU011B

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