Internal Control Module Software Incompatibility
2003-2009 Toyota 4Runner 4.7L V8
Description
Software version mismatch between communicating modules causing data interpretation errors.
Symptoms
- Warning lights on
- Systems behaving erratically
- Features not working correctly after update
- Communication errors between modules
Common Causes
- Module software not updated together
- Partial software update
- Incorrect software version flashed
- Aftermarket module with wrong software
Diagnostic Steps
- Check software versions on all modules
- Compare to required version table
- Perform full vehicle software update
- Check for TSBs regarding software updates
Repair Notes
Perform complete vehicle software update. All related modules must be updated together.
Related Codes
Other Network Codes
- U0001High Speed CAN Communication Bus
- U0001High Speed CAN Communication Bus
- U0002High Speed CAN Communication Bus Performance
- U0002High Speed CAN Communication Bus Performance
- U0003High Speed CAN Communication Bus (+) Open
- U0003High Speed CAN Communication Bus (+) Open
- U0004High Speed CAN Communication Bus (+) Low
- U0004High Speed CAN Communication Bus (+) Low
- U0005High Speed CAN Communication Bus (+) High
- U0005High Speed CAN Communication Bus (+) High
U0300 on Other Vehicles
Toyota 4Runner
2003-2009 4.0L V6
Toyota 4Runner
2010-2024 4.0L V6
Toyota 86
2017-2020 2.0L H4
Toyota Alphard
2023-2025 2.4L I4 Turbo T24A-FTS
Toyota Alphard
2023-2025 2.5L I4 Hybrid A25A-FXS
Toyota Altezza
1998-2005 2.0L I4 3S-GE BEAMS
Toyota Altezza
1998-2005 2.0L I6 1G-FE
Toyota Aqua
2011-2021 1.5L I4 Hybrid 1NZ-FXE
Common Questions
What does code U0300 mean on a 2003-2009 Toyota 4Runner?
U0300 stands for "Internal Control Module Software Incompatibility". Software version mismatch between communicating modules causing data interpretation errors.
What are the symptoms of U0300 on a Toyota 4Runner?
Common symptoms of U0300 include: Warning lights on, Systems behaving erratically, Features not working correctly after update, Communication errors between modules.
What causes U0300 on a 2003-2009 Toyota 4Runner?
Common causes of U0300 include: Module software not updated together, Partial software update, Incorrect software version flashed, Aftermarket module with wrong software.