P0600 OBD-II Trouble Code: Serial Communication Link Malfunction

Check Engine Light

P0600 code definition

The P0600 code is a diagnostic trouble code that points to a malfunction in the communication link of the ECU. This code may be seen with a wide variety of other codes in addition to ABS and traction control system codes.

What the P0600 code means

P0600 means that the ECU has lost the connection with one of its many controllers more than once. When this code is set the ECU triggers the Check Engine Light to be displayed on the dashboard and a failsafe mode enacted.

The failsafe mode is to prevent further damage and protect the vehicle. Failsafe mode will remain in effect until the normal operation is detected or the vehicle is repaired.

What causes the P0600 code?

  • Failing ECU or the ECU has failed
  • Low battery voltage
  • ECU wiring harness open, short or poor electrical connection

What are the symptoms of the P0600 code?

  • The Check Engine Light will be illuminated
  • ABS and traction control system lights may illuminate
  • The vehicle runs poorly
  • Has trouble staying running
  • Engine may not start
  • Transmission may not shift properly

How does a mechanic diagnose the P0600 code?

  • The first step for any qualified technician is to use the scan tool to check for any codes including history and pending codes.

  • Freeze frame data for every code will be checked to see what conditions the vehicle was under when the code was triggered.

  • All the codes will be cleared and a test drive performed to duplicate the symptoms.

  • Next, a visual inspection will be performed looking for damaged, worn, or loose components.

  • Battery voltage will be checked next to make sure it is within specifications

  • Next, a multimeter will be used to check for proper continuity of the power and ground circuits of the ECU.

  • Lastly, the manufacturer’s ECU testing procedure will be done. This will vary from vehicle to vehicle depending on make and model.

Common mistakes when diagnosing the P0600 code

The most common mistake seen is when the ECU claimed to be faulty when the low battery voltage was the real cause.

Always follow diagnostic procedures without skipping any steps and complete steps in the proper order to avoid mistakes with P0600.

How serious is the P0600 code?

The P0600 malfunction may cause intermittent and erratic symptoms that affect normal operation of the vehicle.

If severe symptom are found, the vehicle should not be driven until it has been repaired. With P0600 the ABS system and traction control system can become disabled so driving in poor weather should be avoided if the ABS light and Traction Control Light are displayed on the dashboard.

What repairs can fix the P0600 code?

  • ECU replacement
  • Diagnosing and repairing the cause of the low battery voltage
  • Repairing or replacing the ECU wiring harness
  • Fixing poor electrical connections

Additional comments for consideration regarding the P0600 code

The ECU controls almost all of the cars systems and when a fault occurs it may disable a wide variety of operations. Always check for proper voltage when diagnosing the P0600 code as low battery voltage can cause many strange symptoms.

Need help with a P0600 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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