Removing and installing SCR catalytic converter: Audi Q7 3.0 TDI (CATA, CCMA, CDUC, CDUD, …)
Step-by-step removing and installing SCR catalytic converter for the Audi Q7 3.0 TDI: 9 steps. What to remove, in what order, and what to check after.
This page covers removing and refitting the SCR catalytic converter on diesel models built on the platform codes listed below, fitted with the engine codes given underneath. Compared with most exhaust work it is quick: the converter is held by a clamp joint, nuts and a few bolts. On cars with air suspension, jacking mode must be switched on before the car goes up and switched off again at the end, otherwise the levelling system tries to correct the ride height. Before the converter can come off, the NOx sender is removed and its connector unplugged, and the reducing agent injector N474 is released at its retaining clip and taken out. Those two components are the delicate parts; handle the injector and sensor carefully and refit both before lowering the car.
🧭 Before you start
Activate jacking mode on air-suspension cars, separate the exhaust at the clamp, remove the NOx sender and unplug its connector. Release the reducing agent injector and detach it, then remove the nuts and bolts and lower the SCR converter out. Install the injector and NOx sender on the new or refitted converter and switch jacking mode off.
Fits: Audi Q7 (4L, 2005–2015)
Don't miss
- Activate jacking mode on air suspension before lifting, and deactivate it when finished.
- Remove the NOx sender before the converter comes down to avoid damaging the probe.
- Release injector N474 at its retaining clip; do not lever on the injector body.
- Use a new clamp or check the old one seals; an exhaust leak upstream skews NOx readings.
Written for this job from the workshop steps below · TorqFix editorial.
🔧 Engine codes this applies to
📋 Procedure
- Activate jacking mode on vehicles with air suspension 43.
- Disconnect exhaust system at clamp (arrows).
- Remove NOx sender 2G687(item 3).
- Unplug electrical connector (5).
- Release retaining clip (arrow) and detach injector for reducing agent N474.
- Remove nuts (1) and bolts (2) and (4) and detach SCR catalytic converter.
- Install injector for reducing agent N474.
- Install NOx sender 2G68723.
- De-activate jacking mode on vehicles with air suspension 43.
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.