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Service bulletin A26162720439811

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.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10093601
Published by NHTSA2017-03-03
Manufacturer's numberA26162720439811
Manufacturer's date2016-04-14
NHTSA componentENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR

NHTSA's summary

THIS BULLETIN INFORMS THE READER TO RECEIVE DIAGNOSIS OR AUTHORIZATION FROM THE TECHNICAL ASSISTANCE CENTER BEFORE REPAIRING AN ISSUE WITH THE CATALYTIC CONVERTER THAT CAUSES DTC P042000

The document

No address for NHTSA's copy can be built for this communication. Ask the dealer for it by the manufacturer's number.

Components

Engine, Exhaust and emissions, Catalytic converter

Trouble codes named

P0420

Vehicles listed
AUDI A42009, 2010
AUDI A52010, 2011
AUDI A5 CABRIOLET2010 to 2011
AUDI ALLROAD2009 to 2010
AUDI Q52010, 2011

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Other bulletins for the same vehicles and component
A011257 2028344-2017-11-08. Service bulletin. 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.
A011665203545442017-03-14. Service bulletin. THIS TECHNICAL SERVICE BULLETIN CONTAINS INSTRUCTIONS FOR PRESSURE WASHING PORTS TO RESOLVE AN "AIR SYSTEM -- ACTION REQUIRED" MESSAGE.