# Service bulletin Circular\-Emissio

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

- Type: Service bulletin
- NHTSA id: 10133328
- Published by NHTSA: 2018\-04\-16
- Manufacturer's number: Circular\-Emissio
- Manufacturer's date: 2018\-02\-19
- NHTSA component: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR

## NHTSA's summary

Over time and mileage and under certain conditions, the factory\-installed catalysts may not perform as required by Federal regulations. If the effectiveness of a catalyst is reduced, this may result in an increase in tailpipe emissions and the vehicle could fail to pass an emissions inspection. ? Added repair availability for A8 \(criteria 4E\) and A6 \(criteria 4F\). ? Updated claiming instructions. ? Note added to repair instructions regarding consequential damage.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2018/MC-10133328-9999.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2018/MC-10133328-0001.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Engine, Exhaust and emissions, Catalytic converter

## Vehicles listed

- 2008 to 2011 AUDI A6
- 2008 AUDI A8
- 2008 to 2009 AUDI S5
- 2010 AUDI S5 CABRIOLET

## Other bulletins for the same vehicles and component

- [Circular \- Emiss](/bulletins/10138345.md), 2018-05-21, Service bulletin: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR. Over time and mileage and under certain conditions, the factory\-installed catalysts may not perform as required by Federal regulations. If the effectiveness of a catalyst is reduced, this may result in an increase in tailpipe emissions and the vehicle could fail to pass an emissions inspection. Updated exhaust clamp part number to reference ETKA
- [Dealer Letter \-](/bulletins/10133330.md), 2018-04-16, Service bulletin: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR. Over time and mileage and under certain conditions, the factory\-installed catalysts may not perform as required by Federal regulations. If the effectiveness of a catalyst is reduced, this may result in an increase in tailpipe emissions and the vehicle could fail to pass an emissions inspection. Launch repair availability for A8 \(criteria 4E\) and A6 \(criteria 4F\).
- [Circular\-Emissio](/bulletins/10133329.md), 2018-04-16, Service bulletin: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR. Over time and mileage and under certain conditions, the factory\-installed catalysts may not perform as required by Federal regulations. If the effectiveness of a catalyst is reduced, this may result in an increase in tailpipe emissions and the vehicle could fail to pass an emissions inspection. Updated exhaust clamp part number for A6 and A8 models
- [A011257 2028344\-](/bulletins/10122803.md), 2017-11-08, Service bulletin: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR; ENGINE AND ENGINE COOLING. Supersedes Technical Service Bulletin Group 01 number 12\-51 dated July 18, 2012. Noises/inconsistent engine operation after cold start during the catalyst heating phase. The customer may interpret this engine roughness as misfiring. To comply with the legal requirements on exhaust gas emissions according to the LEV\-1 and LEV\-2 standards, a high exhaust gas quality must be ensured. The necessary catalyst only operates at a temperature over 300°C \(572°F\). To achieve this, the catalyst is heated up. The catalyst heating phase is achieved by a late ignition angles and by introducing additional fresh air to the exhaust valves \(secondary air system\). Late ignition angles make sure that the exhaust gas from the cylinders has a higher temperature. This exhaust gas includes fuel that is un\-burnt, and was deliberately injected into great quantities. The secondary air system adds fresh air to the exhaust gas as it leaves the cylinder and the extra fuel is burnt. As a result, the temperature of the exhaust gas and of the catalyst increases quickly. The afterburning in the exhaust manifold before catalyst changes the sound characteristic of the engine. This heating\-up of the catalyst, including afterburning, is normal and has no effect on the service life of the engine. During this catalyst heating phase the engine has increased idle speed, may have increased vibrations, and a different sound characteristic. Depending on conditions the time of the catalyst heating phase varies.
- [A01166520354544](/bulletins/10094894.md), 2017-03-14, Service bulletin: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR. THIS TECHNICAL SERVICE BULLETIN CONTAINS INSTRUCTIONS FOR PRESSURE WASHING PORTS TO RESOLVE AN "AIR SYSTEM \-\- ACTION REQUIRED" MESSAGE.

JSON: [/v1/bulletins/10133328](/v1/bulletins/10133328)

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