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P0600 — Serial Communication Link

Generic OBD-II · all makesPowertrain (engine & transmission)

P0600 indicates a problem with the vehicle’s internal serial communication link, which is the data channel used by modules to exchange information.

Symptoms

What causes it — most likely first

1. Faulty communication cable

A damaged or frayed wiring harness can interrupt data transmission between modules.

2. Loose or corroded connector pins

Poor electrical contact at connectors can cause intermittent signal loss.

3. Module software glitch

A malfunctioning control module may generate erroneous communication errors.

4. Environmental interference

External electromagnetic interference can disrupt serial data if shielding is inadequate.

5. PCM/ECM failure

Rarely, the central computer itself can develop a fault that manifests as a communication error.

How it's diagnosed

  1. Check wiring harness for visible damage or corrosion.
  2. Inspect and clean connector pins for continuity.
  3. Use a scan tool to read specific communication-related trouble codes or data streams.
  4. Test modules individually for proper operation and verify firmware versions.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make

Frequently asked

Is the PCM always the cause of P0600?

No, most P0600 codes stem from wiring or connector issues; only in rare cases is the PCM itself defective.

Can I fix this by resetting the ECU?

A reset may clear the code temporarily, but if the underlying wiring or connector problem remains, the code will return.

What should I look for in the wiring harness?

Examine for frayed insulation, pinched wires, or signs of corrosion, especially near the engine control module.