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U0418 Invalid Data Received From Brake System Control Module A

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U0418 says a node rejects the content of frames from brake system control module A, on many cars the unit that combines ABS, stability control and brake boost. GM's 2025 tables are detailed: the engine controller tests brake status signals for bad counters, protection values or checksums, 8 faults in 18 checks give Type A with MIL after one trip; the TCM runs the same test as Type B, the BCM demands 15 bad of 16, and the front camera rates its check Special Type C and only disables adaptive cruise. Saab's 9-5 list adds sub-types 71, 72 and 74. FCA notes for the 2021 Jeep Cherokee 2.4 L that U0418 may set falsely below 10 V and reflashes the PCM (18-078-22); BrightDrop 24-NA-107 forbids repairs for it on the Zevo 600. U0129 is lost contact, U0318 software.

Likely causes

Low battery voltage (below about 10 V) during start or standstill
Engine or transmission controller software reacting too sensitively; update available
Loose connector or harness fault disturbing the chassis bus
Brake system control module internally faulty

Symptoms

  • Check engine light
  • Adaptive cruise, stop-start or driver assistance unavailable
  • Brake or stability warning in the cluster

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–2,000
Time0.3–4 h

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

Parts involved

brake system control modulecan bus wiring

Related codes

U0129U0318U04B5U0415U0416

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