Chassis, generic

C0420 Adaptive Cruise Control Module Internal Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

No public document shows a maker using C0420. It does not appear in the openly accessible J2012 lists, in GM's PIP5094 or in the NHTSA bulletin index, so only the module from the title is covered. The ACC module evaluates the radar data and requests engine torque and braking to keep speed and gap, as Bosch outlines. Faults of the module itself are mostly cured by software: Jeep reprograms the ACC module of the 2024 Compass when C0063-9A, a yaw rate operating-condition code, is set with the check engine lamp, naming ACC software as the cause; Land Rover corrected a wrong ACC module calibration on 2019 Range Rover Sport mild hybrids in service action N343NAS1. An internal performance fault normally disables adaptive cruise and related assists until the module passes its self-test.

Likely causes

ACC module software or calibration out of date
Low or unstable supply voltage during self-test
Internal hardware fault of the ACC module

Symptoms

  • Adaptive cruise control and related assists unavailable
  • Driver assist warning in the instrument cluster

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–1,500
Time0.3–2 h

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

Parts involved

acc modulevehicle power supplycommunication bus

Related codes

C0410

References: bosch-mobility.com, static.nhtsa.gov, static.nhtsa.gov.