Fault code P0600 – serial communication link malfunction

Fault code P0600 is called “Serial Communication Link Malfunction” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0600

Error code P0600 indicates a fault in the wiring between the electronic control module (ECM) and one of its supporting control modules. This fault code is common and applies to all computer-controlled vehicles.

Fault code P0600 – serial communication link malfunction

In other words, if this fault occurs, your vehicle’s ECM has lost control of one or more actuator modules. Modern vehicles may have up to 18 modules that are controlled by the main engine control unit.

It is controlled via the CAN (Can Bus Automotive Network) controller network. Which is a series of wiring harnesses from the ECM to the controllers.

The controllers controlled by the ECM are responsible for making most of the functions of your vehicle work. When code P0600 is set, the ECM detects a loss of communication and control over one or more of these controllers for eight consecutive starts.

Symptoms of vehicle malfunctions

The main signal that an error P0600 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be stored in the memory as a malfunction).
  2. The ABS and traction control system light may illuminate.
  3. Transmission light illuminated (transmission may not shift properly).
  4. Floating revolutions, and attempts to stall at idle.
  5. Reduced engine power.
  6. Increased fuel consumption.
  7. Problems with a particular system, indicating a possible loss of communication in that area.

Code P0600 indicates a communication failure between the ECM and any control module. Depending on which module has lost communication, the error may be severe or moderate.

Factors that can cause this error code

The error code P0600 can mean that one or more of the following problems have occurred:

  • The electronic control module (ECM) has failed.
  • Low battery voltage.
  • Open or short circuit in the wiring harness related to the engine control module (ECM).
  • Loose or damaged connectors.
  • Poor grounding is a common cause.
  • CAN bus may be faulty and have a short to ground or wire breakage.

How to fix or reset OBD-2 code P0600

Some suggested steps for troubleshooting and fix the error code P0600:

  1. Read all stored data and error codes with an OBD-II scan tool. To find out when and under what circumstances error P0600 appeared.
  2. Clear the error codes from the computer memory and test-drive the vehicle to find out if the malfunction appears again.
  3. If the error code appears again, visually inspect the engine control module (ECM) electrical leads and connector.
  4. Measure battery voltage and compare it to the manufacturer’s specification.
  5. Verify continuity of ECM power and ground using a multimeter.
  6. Evaluate the operation of the ECM following the vehicle manufacturer’s procedure.
  7. Clear the error code from the computer memory again, and test drive the vehicle to see if the problem is resolved.

Diagnose and repair of problems

In some vehicles, a memory saver must be installed before the battery is disconnected in order to retain the memory of the engine-ECU. If the engine-ECU loses its memory due to lack of power, the vehicle will not start until it is reprogrammed by your dealer.

Wiring checks should be performed systematically using the wiring diagram and pin values. If you check the wrong terminal, the ECM or associated module may fail.

To diagnose the P0600 code, start the vehicle’s engine and monitor all systems in real time. The scanner will show the values of the pins and working modules, and will indicate any abnormalities.

Usually, when scanning, symptoms or an additional error code may appear that can direct you to the system in question where the communication failure occurred.

After identifying the system from the symptoms or additional code, check the connections for inconsistencies, such as loose or corroded terminals. Refer to the wiring diagrams in the service manual when troubleshooting.

On which vehicles does this problem occur most frequently

Fault code P0600 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi (A6)
  • BMW (750, E39)
  • Chrysler
  • Dodge (Caravan, Stratus)
  • Ford
  • Honda
  • Hyundai (Sonata)
  • Infiniti (I30)
  • Jeep (Wrangler)
  • Mazda (6, CX-5)
  • Mercedes-Benz (A190, C320, W168, W203, W211)
  • Mitsubishi (Fuso)
  • Nissan (AD, Almera, Bluebird Sylphy, Maxima, Serena, Sunny)
  • Peugeot (Boxer)
  • Porsche (Cayenne)
  • Renault
  • Ssangyong (Kyron, Rexton, Rodius)
  • Subaru (Forester, Impreza, Legacy, Outback)
  • Volkswagen (Beetle, Golf, Passat, Touareg)
  • Volvo (S40, S80)
  • LADA (Granta, Priora)

Fault code P0600 can sometimes be found with other errors. The most common are the following: P0130, P0136, P0325, P0500, P0702, P0720.


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