Network, generic

U0408 Invalid Data Received From Throttle Actuator Control Module

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

U0408 points to messages from the throttle actuator control module that the receiver, usually the ECM/PCM, judges invalid: implausible content, a failed checksum or counter, or a value outside its range. Most vehicles integrate throttle control in the engine controller, so a separate TAC module and therefore this code are uncommon; no manufacturer documents U0408 publicly. Ford's 2012 OBD summary illustrates the U04xx logic with U0401, which the TCM stores when ECM torque or pedal data are faulted. Because the throttle meters intake air, CARB's comprehensive component rules apply, and a MIL together with reduced power or a limp mode is likely. U0107 means lost contact, U0308 a software mismatch with the same module.

Likely causes

Damaged bus wire or poor connector contact at the throttle module
Throttle actuator control module internally faulty
Software of throttle module and ECM do not match
Low or unstable supply voltage

Symptoms

  • Check engine light on
  • Limp mode with reduced throttle response
  • Unstable idle or stalling

Repair estimate

DifficultyMediumWorkshop 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

throttle actuator control moduleengine control modulecan bus wiring

Related codes

U0107U0308U0401U0406

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