Chassis, generic

C0538 Motor Control B Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Motor control B reads low: a channel-B output is held near ground. Besides a direct short of a motor lead to the body, the Bosch patent US5329238 also covers the case where both terminals deviate at once while driven, which it reads as a short across the motor itself or between its two lines. Driver chips such as TI's DRV8873-Q1 react to a short to ground through their overcurrent protection and switch the half-bridge off. J2012 does not tie the code to a specific motor and no public manufacturer assignment of C0538 appears in the sources reviewed. Inspect harness routing near moving parts and connectors for water before replacing the motor or module; channel A uses C0533 for the same fault.

Likely causes

Motor B lead shorted to body near moving parts
Short across motor B or between its two lines
Water in the connector of motor B

Symptoms

  • Warning lamp of the affected system on
  • Motor B does not start

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–1,200
Time0.5–3 h

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

Parts involved

chassis motor bmotor wiring

Related codes

C0536C0537C0533

References: patents.google.com, ti.com.