P0600 Code Meaning and Next Steps

First checks take 10 to 20 minutes for the first checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!The engine starts stalling, losing power sharply, or the warning light flashes.
!The vehicle begins to run erratically or enters limp mode while the code is active.

If the light is steady and the vehicle still drives normally: Often yes for a short time, but it should not be ignored.

What to check first

Step-by-step checks

1
Free - no tools
Check whether the battery is weak or recently disconnected, because low voltage can trigger network faults
2
Free - no tools
Inspect visible module connectors and harnesses for corrosion, looseness, or water intrusion
3
Basic tool needed
Notice whether multiple warning lights or unrelated systems stopped working at the same time
4
Basic tool needed
If scan data is available, see whether one module is missing from the network rather than assuming the first code is the whole story
5
Basic tool needed
If the issue appeared after a repair or aftermarket accessory install, inspect those circuits carefully

If the code returns

-If other modules also report communication faults, the network or power supply rises on the list.
-If the fault returns after a battery reset, wiring or module-side trouble is more likely than a temporary glitch.
-If only one module is missing, focus on its power, ground, and communication path before replacing it.

Background

What this code means

P0600 is a generic OBD-II code for a serial communication link malfunction.

That usually means the ECU is having trouble talking to another module on the network or is seeing the communication path behave incorrectly.

Diagnosis

Common causes

Most common

Network wiring or connector fault

A loose or damaged connection can interrupt serial communication.

Common

Low system voltage

Weak battery or charging issues can destabilize module communication.

Common

Module communication failure

A module may no longer respond on the network.

Possible

Aftermarket wiring issue

Added accessories can disturb the data line or power feed.

Avoid these mistakes

What not to do

xDo not replace a control module first if there is obvious wiring, connector, or power-supply damage.
xDo not assume a module code always means the module itself is bad before checking the supporting circuit.

Parts

Parts that may need replacing

PartTypical costNotes

Battery or charging system test$0-$50Often the first place to check before replacing modules.

Connector or harness repair$20-$150Relevant when corrosion or damage is visible.

Control module diagnosisVariesNeeded only after power, ground, and network checks are done.

Related OBD codes

P0601

P0601 usually means the internal control module memory checksum is incorrect.

P0602

P0602 usually means the control module has been programmed incorrectly.

P0604

P0604 usually means the internal control module random access memory has failed.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0600 was expanded around common serial communication faults, especially wiring problems, low voltage, and module network issues.

This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.

This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.

Last reviewed: 2026-04-10

Reference: Open reference

P0600 - P0600 Usually Means There Is a Serial Communication Link Malfunction