Network, generic

U01B2 Lost Communication With Planetary Gear Set Control Module

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Hybrid transmissions such as the two-mode system developed by GM, Daimler, Chrysler and BMW use two or three planetary gear sets plus clutches to switch between power-split and fixed-ratio operation. A planetary gear set control module would run those shift elements and report their state to the hybrid or transmission controller. U01B2 means this module has gone off the network, so the controller no longer knows which gear-set state is engaged. No manufacturer documents the code publicly. CARB 1968.2 counts transmission and hybrid control units among the monitored powertrain parts, so a MIL is likely wherever the code is used. Expect a hybrid system warning together with reduced power or a limited fallback mode; U04B3 covers implausible data from the same module.

Likely causes

Damaged CAN wiring or connector at the transmission
Module without supply voltage or ground
Planetary gear set control module faulty

Symptoms

  • Hybrid system warning
  • Reduced power or limited fallback mode
  • MIL on

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–5 h

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

Parts involved

planetary gear modulecan bus

Related codes

U04B3U0101U0293

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