Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Exhaust System Components, Removing and Installing
For all Exhaust System, Emission control component locations. Refer to → 26 - EXHAUST SYSTEM, EMISSION CONTROLS
For all Exhaust System, Emission control removal/installation procedures and torque specifications. Refer to → 26 - EXHAUST SYSTEM, EMISSION CONTROLS
Check the Technical Bulletins for information that may supersede any information included in this article.
- All manufacturers special tools as well as common tools may contain a manufacturer specific part number. These tools may be substituted with an equivalent aftermarket tool or are available for purchase through Audi.
- Manufacturers special tools as well as common tools that contain a manufacturer specific part number may be referenced in the test procedure illustrations showing the tool use or installation. If the manufacturer specific tool is not being used, an equivalent aftermarket tool may be installed in the same manner as the manufacturers special tool.
Three Way Catalytic Converter (TWC), checking
Test requirements
- Battery voltage at least 12.5 volts.
- Oxygen Sensors OK.
- No leaks or damage to exhaust system.
Function test
- Perform the function test in Diagnostic Mode 06. Refer to → Diagnostic Mode 06: Checking Test Results of Components that are not Continuously Monitored .
- End diagnosis and switch the ignition off.
If the specified values are exceeded:
- Check the exhaust system for leaks.
- If necessary, repair the leak in the exhaust system.
- Erase the DTC memory. Refer to → Diagnostic Mode 03: Interrogating Fault Memory .
- Perform a road test to verify Repair.
If the DTC does not return:
Repair complete, Generate readiness code. Refer to → Readiness Code .
- End diagnosis.
If no leaks are found in the exhaust system:
- Replace the catalytic converter including front exhaust pipe. Refer to 26 - EXHAUST SYSTEM, EMISSION CONTROLS .
Final procedures
After the Repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory.
- If necessary, erase the DTC memory. Refer to Diagnostic Mode 04: Reset/delete Diagnostic Data .
- If the DTC memory was erased, generate readiness code. Refer to Readiness Code .
End of diagnosis
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.