Network, generic

U0442 Invalid Data Received From ECM/PCM B

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

ECM/PCM B stands for a second engine or powertrain controller where a car carries more than one such unit; U0442 means its frames reach a receiver with invalid content, while U0115 means they stop arriving. Mazda applies the code in its own way: bulletin 01-015/18 for the 2018 Mazda6 and CX-5 and the 2019 CX-3 and MX-5 describes the TCM of automatic models flagging invalid PCM data, together with P061B and U0401, when the driver lets go of the brake during cranking. The PCM then enters a fail-safe mode with limited engine speed, and new PCM software cures the false detection. Mercedes-Benz lists U044287 with U014687 when a software conflict in the 48 V battery switches on the check engine light (LI54.21-P-078926). Expect the MIL and, depending on design, reduced power.

Likely causes

Control logic in the engine or powertrain software too sensitive, update available
Software levels of sending and receiving units do not match after an update
Bus wiring, connector or supply fault at the second powertrain controller

Symptoms

  • Check engine light on
  • Fail-safe mode with limited engine speed or lack of power
  • Transmission codes stored alongside engine codes

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–800
Time0.5–2.5 h

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

Parts involved

ecm pcm bcan bus wiring

Related codes

U0115U0401U0441

References: static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.