Skip the auto shop - Our mechanics make house calls

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
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How Long Does a Fuel Filler Neck Last?
Getting gas from the pump to your gas tank is the only way to keep a car going. The fuel filler neck is a metal tube that is welded to the...
How Long Does a Vacuum Brake Booster Check Valve Last?
The braking system on your car requires a lot of pressure. The vacuum booster is one of the main sources of this pressure. This booster will take the pressure that...
P0121 OBD-II Trouble Code: TPS "A" Circuit Range Performance Problem
P0121 code definition Throttle Pedal Position Sensor/Switch (TPS) A Circuit Range Performance Problem...


Related questions

Q: Prnds flashing lights anb p0777 code

Hello. For this vehicle, it appears that the solenoids are located inside the transmission. For many vehicles the transmission control solenoids are bolted to the exterior of the transmission, however for this vehicle the solenoids are part of the transmission...

Q: Engine light is on, suspect catalytic converter

If your catalytic converter was having an issue as diagnosed by the dealership and it has been modified to correct the issue with no success, I would start by recommending a replacement of the catalytic converter. It would also be...

Q: Instrument cluster is off with a P0600 reading

Hello there, the P0600 code is not one that is normally seen on your 2003 Mercedes ML350. The P0600 code tells us there is a communication link issue with the ECU. This may have been caused by the fuel pump...