Network, generic

U042C Invalid Data Received From Chassis Control Module B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U042C refers to a second chassis controller, labelled B, where chassis tasks are split between two units. It is stored when that module's frames still arrive but carry a bad counter, checksum or implausible values. No manufacturer documents U042C or the B module publicly; the only public assignment found concerns module A, which GM's 2020 transmission tables equate with the integrated chassis control module. CARB asks emission-related controllers to flag faulty digital communication as well as its absence, which mirrors the pair U012B and U042C, although a chassis unit usually lies outside that rule. B alone points to that module or its harness, B with U042B to shared supply, gateway or bus wiring. A MIL is not expected; chassis messages are likely. U012B is lost contact.

Likely causes

Software fault in chassis module B or the receiver
Supply, ground or gateway problem affecting the module's messages
Chassis control module B faulty

Symptoms

  • Chassis or suspension warning in the cluster
  • Chassis function handled by module B inactive

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–900
Time0.3–2.5 h

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

Parts involved

chassis module b

Related codes

U012BU042BU012A

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