CorollaFix

P0600 on Toyota Corolla E140: Serial Communication Link Malfunction

Short answer: P0600 means “Serial Communication Link Malfunction”. The car’s computer has found a fault in the ECM system and turns on the Check engine light (MIL). First check: check all battery and ECM power and earth connections first.

Standard OBD-II code Same meaning on all cars (SAE J2012). Not checked against this car’s factory manual.

Code
P0600
System
ECM
Dashboard light
Check engine light (MIL)
Applies to
Generic OBD-II meaning. Not every code is used by this car.
Confidence
medium (generic OBD-II definition, not checked against the factory manual for this car)
Source
obd-codes.com

Symptoms and when it is set

  1. Check engine light on
  2. An inexperienced technician may begin by attempting to diagnose the affected system rather than the loss of communication. If the ECM is not…
  3. ABS light illuminated
  4. Transmission light illuminated (vehicle may not shift properly)
  5. Big drop in fuel economy
  6. Driveability problems may occur, such as stalling at an idle, rough running and poor acceleration, or

Likely causes

  1. Experience has proven that a poor connection or failed ECM driver is the root cause of this code. For the most part, the ECM acts as a ground to…
  2. A loose or corroded connector is more likely than a frayed or broken wire between both devices. Poor grounds are another plausible cause. The ECM,…
  3. The wiring harness or Can Bus may be defective and have a short to ground or an open wire

What to check, in order

  1. Check all battery and ECM power and earth connections first
  2. Read every stored code; an ECM fault is rare, wiring faults are common
  3. Have a specialist confirm before replacing the ECM

Related on this car

Same code on other cars

← P0563 P0604 →

Clearing the code does not fix the fault. If it comes back, the problem is still there. For brakes, airbags and steering, see a trained mechanic.