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2020 BMW I3
42 kWh Single Motor RWD•RWD•AUTOMATIC•ev
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Repairs0Labor314Torque2935Fluid5DTC1125Battery1Maintenance0Recalls0
P3024critical severityPowertrain

CVT Ratio Control System Stuck

on 2020 BMW i3 42 kWh Single Motor RWD · RWD

What this code means

The CVT ratio control system is unable to change the transmission ratio. The pulleys may be mechanically seized or the stepper motor has failed.

Symptoms

  • Check Engine Light
  • Engine revs stay constant regardless of speed
  • No ratio change during acceleration
  • Sudden RPM changes
  • Vehicle feels stuck in one gear
  • Harsh engagement from stop

Common causes

  • Stepper motor failure
  • Pulley guide rail damage
  • Hydraulic valve body stuck
  • Belt/chain jammed
  • Foreign object in pulley mechanism

Diagnostic steps

  1. Monitor CVT ratio PID during driving
  2. Command ratio change with scan tool
  3. Check stepper motor operation
  4. Inspect hydraulic valve body operation
  5. Check for metallic debris in fluid

Repair notes

CVT likely requires removal and disassembly. Stepper motor or valve body replacement. Severe cases require transmission replacement.

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