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DTC codes / Mitsubishi codes / P1600

P1600 · MitsubishiSerial Communication Link

P1600 on Mitsubishi vehicles indicates that the engine control module (ECM) has detected a failure in the serial communication link that connects it to other onboard computers, such as the transmission control module or the anti-lock brake system module. The ECM monitors a dedicated serial data line and sets this code when the expected messages are missing, corrupted, or the line is electrically faulty.

SystemPowertrain
Code typeMitsubishi specific
SeverityMedium
Fix difficultyProfessional
AreaComputer and output circuits

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Rough running or stalling if the communication failure affects engine management data
  • Transmission may shift harshly or enter limp mode if the transmission control module cannot communicate
  • Multiple warning lights on the dashboard (ABS, airbag, etc.) due to shared communication bus issues
  • Intermittent starting problems or a no-start condition if the ECM cannot handshake with the immobilizer
  • Erratic gauge readings or unexplained electrical glitches

Common causes, most likely first

  1. Damaged or corroded wiring in the serial communication bus between the ECM and other modules
  2. Poor electrical connection at the ECM connectors, often due to water intrusion or loose pins
  3. Failed transmission control module or other module on the same communication link
  4. Internal fault in the ECM affecting its communication interface
  5. Aftermarket electronic accessories improperly tapped into the data bus
  6. Blown fuse or poor ground connection for the communication circuit

How to diagnose and fix it

  1. Inspect the serial communication wiring for obvious damage, corrosion, or loose connectors, especially at the ECM and transmission control module
  2. Check all fuses related to the ECM and communication system, and verify battery voltage and ground connections
  3. Use a factory-level scan tool to read communication codes from all modules and perform a network integrity test
  4. Measure resistance and continuity on the serial data lines to identify opens or shorts
  5. Substitute a known-good module (if possible) to isolate a faulty ECM or other module
  6. Repair or replace damaged wiring and connectors, then clear codes and verify communication is restored
  7. If the ECM is confirmed faulty, replace and reprogram it according to Mitsubishi service procedures

Serial Link Faults Often Misdiagnosed

  • A weak or failing battery can cause voltage drops that disrupt serial communication, setting P1600 without any wiring fault.
  • Aftermarket alarms or audio equipment tapped into the data bus are a common cause of communication errors that mimic a failed module.
  • The code may be stored intermittently due to a poor ground connection at the ECM, which can be overlooked when only the data lines are checked.
  • P1600 can be set by a faulty transmission control module even when the engine runs perfectly, leading to unnecessary ECM replacement.
  • Always check for technical service bulletins (TSBs) for the specific Mitsubishi model, as some communication issues are addressed by software updates.

Can I keep driving with P1600?

If the vehicle drives normally, you can proceed to a repair shop, but avoid long trips or heavy loads. If the engine runs rough, the transmission shifts erratically, or multiple warning lights are on, stop driving and have the vehicle towed to prevent damage or unsafe operation.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Mitsubishi vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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