Readiness Test (UDS only)
From Ross-Tech Wiki
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.