Network, generic

U0449 Invalid Data Received From Serial Data Gateway Module C

Check engine lightUsually off

EmissionsNot relevant

Drive cycleNot required

Limp modeNo

U0449 points at serial data gateway module C; its lost-contact partner is U0148. The receiver logs it when C keeps transmitting, yet the content breaks the rules agreed for that message, for instance a wrong length, a frozen counter or a bad checksum. No manufacturer documents U0449 publicly. How strictly receivers police gateway traffic is visible at GM: in one 2024 table the ECM checks the data length code of several frames that the gateway forwards from two CAN buses, and a wrong length lasting 10 s sets the gateway A code as a two-trip fault, while a missing frame sets a separate maker-specific code. A third gateway mostly appears in vehicles with many separate networks. Symptoms depend on which networks C joins; several unrelated warnings at once are typical.

Likely causes

Gateway C software sends frames in a layout the receiver does not expect

Wiring, termination or connector fault on a network served by gateway C

Low voltage or poor ground at gateway C

Symptoms

Several unrelated warnings in the cluster
Functions on one network segment unavailable

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€60–900

Time0.3–2.5 h

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

Parts involved

gateway module ccan bus wiring

Related codes

U0148 U0448 U044A

References: gsi.ext.gm.com, gsi.ext.gm.com.