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2011 KIA OPTIMA
2.4L I4•FWD•AUTOMATIC•gas
5 active safety recalls on this vehicle — view recalls
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Repairs0Labor548Torque4528Fluid6DTC893Battery1Maintenance0Recalls5
P1602high severityPowertrain

TCM Serial Communication Problem

on 2011 Kia Optima 2.4L I4 · FWD

What this code means

The PCM has detected a serial communication problem with the Transmission Control Module. Data exchange between the PCM and TCM is interrupted or corrupted, preventing coordinated powertrain operation.

Symptoms

  • Check Engine Light
  • Transmission in limp mode
  • Harsh shifting
  • No upshifts or downshifts
  • Cruise control inoperative

Common causes

  • Faulty TCM
  • CAN bus wiring damage
  • Corroded CAN bus connector
  • TCM power or ground issue
  • PCM CAN bus driver failure

Diagnostic steps

  1. Check TCM power supply and ground connections
  2. Inspect CAN bus wiring between PCM and TCM
  3. Test CAN bus resistance (approximately 60 ohms between CAN-H and CAN-L)
  4. Attempt to communicate with TCM using scan tool
  5. Check for TCM-specific DTCs

Repair notes

Repair CAN bus wiring or connectors; replace the TCM if it has failed internally.

Other Powertrain codes on this vehicle

🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years. Spot an error? Use the Help link above — a human reads every report.
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