Network, generic

U0402 Invalid Data Received From TCM

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

U0402 is the reverse case of U0401: the engine controller or another listener receives the transmission controller's frames but rejects their content. GM's 2025 ECM checks counter, protection value and checksum of the estimated-gear and general transmission information signals, flags a fault at 8 errors among 18 checks, Type A after one trip; the body controller uses 15 of 16 and Type B. Saab's 2011 list names sub-codes 72 (counter), 73 (parity) and 74 (checksum). On the 2022 Ram 1500 5.7 L eTorque the PCM, once U0402 is set, refuses torque requests from the TCM, the gearbox falls into a fixed limp gear and the MIL lights; PCM software (18-001-23) cures it. On 2014-2015 Cherokee and 200 nine-speeds FCA traced U0402 and a rough 5-4 downshift to the C-clutch snap ring (21-008-15). U0101 is lost contact.

Likely causes

Software of PCM or TCM (update available)
Internal transmission fault making the TCM send implausible values
Disturbed CAN traffic from connectors, wiring or low voltage
Transmission control module internally faulty

Symptoms

  • Check engine light
  • Transmission stuck in a fixed gear (limp mode)
  • Harsh or delayed shifts

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–2,500
Time0.3–8 h

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

Parts involved

tcmcan bus wiring

Related codes

U0101U0302U0401U0400

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