EngineLightCodes
Powertrain code

P0600 Serial Communication Link

Severity
Fix soon
Typical repair cost
$110–$1,650
Do it yourself
Shop job
Shop time
1–4 hours

P0600 means a serial data link that the module relies on has failed.

How the engine computer detects it

At Ford it is the internal link between the main processor and the monitoring processor ('quizzer') of the electronic throttle safety concept: if data cannot be exchanged or check bytes are invalid, the code sets within about a second (diesel: 5 s), usually with the check engine and wrench lamps and a throttle failure mode such as an RPM limit. Subaru (also sold as Saab 9-2X) uses it for the dedicated serial line between engine and transmission module. GM does not use P0600. Lost CAN messages from a named module are reported separately as U0100 and following. Before replacing anything: check battery, grounds and supply, look for a software bulletin, reprogram with a stable power supply, and replace the module only if the code returns.

Written from public technical sources and not yet checked by a mechanic. How we write these pages

Symptoms

  • Check engine light, at Ford also the wrench lamp
  • Reduced power or RPM limit (throttle failure mode)
  • Harsh shifts or transmission limp mode where the line links engine and transmission
  • Other monitors such as the catalyst monitor do not run

Common causes

  1. Internal module fault in the processor-to-processor link Most likely
  2. Faulty module software (update available) Possible
  3. Open or short in a dedicated serial line between engine and transmission module (e.g. Subaru) Possible
  4. Low voltage, voltage dips or a poor ground or supply at the module Possible
  5. Fault in the transmission module at the other end of the line Less likely

How to diagnose P0600

  1. Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
  2. Inspect the parts involved: engine control module, transmission control module, serial data line.
  3. Work through the causes above from most to least likely, cheapest checks first.
  4. Clear the code and drive a full drive cycle to confirm the repair held.

Reading the code

P
Powertrain
0
Generic (SAE) code
6
Computer and output circuits
00
Specific fault

Questions drivers ask

Can I drive with code P0600?

Drive gently and only as far as you need to. The engine computer may limit power to protect the engine, so avoid highways and heavy traffic until it's fixed. If the check engine light starts flashing, pull over.

Will my car pass an emissions inspection with P0600?

Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.

This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.