Readiness Test (UDS only)

Readiness Test (UDS only)

• This Tech Tip demonstrates how to perform the [Automatic test sequence] for UDS-based Gasoline Engine Control Modules (ECMs) using VCDS.
• Basic Setting performs the required Readiness Tests on modern VW/Audi vehicles equipped with UDS protocol engine controllers.
• Use of this procedure is typically for after repairs or component replacement affecting emissions-related systems, or after clearing DTCs.

If you are experiencing difficulty completing the readiness procedure, please refer to the Special Notes section below.

Special Tools

• VCDS (VAG-COM Diagnostic System)

Prerequisites

• Engine must be running
• All electrical consumers OFF (A/C, headlights, rear defrost, seat heaters, etc.)
• No active Diagnostic Trouble Codes (DTCs) – Clear all fault codes prior to starting the test
• Engine coolant temperature must be at least 80°C (176°F)
• Must be performed outside or in a well-ventilated area, and never park the vehicle over combustible materials.

Workshop Procedure with VCDS

• Connect to the vehicle using VCDS.

• Go to [01 - Engine]

• Check for and clear any fault codes.

• Click on the [Basic Settings] button.

• Select [Automatic test sequence] or [Automatic test procedure] from the available list.

• Click on the [Show Measuring Data] checkbox and include the following Measuring Values:

Measuring Value	Description
IDE00450	Operating Instructions – Follow all prompts provided here
IDE00451	Currently Running Routine – Indicates the test currently in progress
IDE00030	Status of Actuator Test – Displays overall status of test procedure
IDE00727	Test Steps Still to Be Performed – Should count down to 0 when complete
IDE00021	Engine Speed – Follow any required RPM prompts shown in Operating Instructions
IDE00025	Coolant Temperature – Should be at or above 80°C before beginning

• Click the [Go] button to begin the Basic Setting procedure.

• When prompted, press and hold both the brake and accelerator pedals simultaneously. Keep them pressed until the test finishes.

• When the test completes successfully, the IDE00450 [Operating Instructions] field will display:

 'System OK'   or   'Finished correctly'

Special Notes

• The duration of the Automatic Test Sequence may vary depending on vehicle platform and engine type.
• If the sequence fails or does not complete, verify that all prerequisites are met, especially coolant temperature and fault-free status.
• This function is only available in UDS-based engine control modules. Non-UDS controllers use a different Readiness procedure, see Repair Manual.
• If the [Go] button is grayed out or unavailable, ensure that the engine is running and that the selected test is supported by the ECU.
• Using VCDS initiates a request to perform the readiness test; the ECU controls the process and may take longer to complete as the vehicle ages.
• Ensure the engine control module has the latest software version installed to avoid readiness issues.
• In some cases, it may be necessary to complete a full OBD drive cycle before attempting the readiness procedure again.