Network, generic

U0448 Invalid Data Received From Serial Data Gateway Module B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0448 concerns serial data gateway module B, a second gateway that some architectures add next to the central unit to bridge further networks; U0147 is lost contact with it. A receiver stores U0448 when B's frames arrive but alive counter, checksum or message authentication do not match. No manufacturer documents U0448 publicly. For gateway A, GM's 2025 tables show what such checks look like: a few failed samples within a short window, MIL treatment that varies by receiver, and assistance functions such as adaptive cruise switched off as a fallback. Audi's Q4 e-tron bulletin shows a faulty gateway leaving several modules reporting it at the same time. Because every message routed through B is affected, symptoms tend to appear on several systems together; software level and supply of module B come first in diagnosis.

Likely causes

Software level of gateway B not matching the other modules
Supply or ground fault at gateway B
Internal fault in gateway module B

Symptoms

  • Warnings from several systems at the same time
  • Assistance or comfort functions on the networks behind gateway B 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

vehicle gateway

Related codes

U0147U0447U0449

References: gsi.ext.gm.com, static.nhtsa.gov.