Network, generic

U0439 Invalid Data Received From All Terrain Control Module

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U0439 relates to the all terrain control module, which manages drive modes for snow, sand, mud or rock and passes the chosen setting to powertrain, brake and suspension controllers. A receiver sets it when mode request, switch state or status frames from this module look invalid. No manufacturer documents U0439 publicly. Ford and Land Rover both call such a unit ATCM: Ford's SSM 54656 for 2025-26 F-150 finds a 4L switch held down by trim, logged in the ATCM, and Land Rover's SSM73849 covers ATCM variants the Pathfinder tester could not recognise, which shows the module also handles off-road switch inputs. If terrain data is invalid, receivers will typically fall back to the normal road setting, so off-road modes or low range may be unavailable. U0138 is lost contact.

Likely causes

Terrain or 4WD mode switch stuck or obstructed by trim
All terrain module software or variant coding wrong
Poor supply, ground or connector at the module

Symptoms

  • Check 4x4 or terrain system message
  • Drive mode selection does not respond

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–800
Time0.3–2 h

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

Parts involved

all terrain module

Related codes

U0138U0437U043A

References: static.nhtsa.gov, static.nhtsa.gov.