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Bulletin Number:(NNN) NNN-NNNN/p>
Date: November 2004
Supplementary fault diagnosis, catalytic converter, T7 and T8
There are certain engine faults that may result in reducing the efficiency of the catalytic converter. If a large quantity of unburned fuel reaches a hot catalytic converter in a short time, it is possible for extreme temperatures to develop within the catalyst. These extreme temperatures may damage the cell structure of the catalytic converter. This damage can result in heightened exhaust back pressure.
There are many types of conditions that may generate the diagnostic trouble code for poor catalytic converter function. Sometimes multiple trips or other specific conditions must occur before the diagnostic trouble code is registered. This may result in a vehicle in the workshop with a developing problem that has not yet registered a diagnostic trouble code.
If there is any uncertainty in such cases over the function of the catalytic converter, a new function in Tech2 can supplement the OBD system by enabling an alternative diagnosis of the catalytic converter in the workshop. The Tech2 diagnosis does not replace the on-board diagnosis in the control module and should be viewed only as a complement to assure a proper diagnosis. This Tech2 diagnosis is designed to detect seriously damaged converters.
In certain markets there is no oxygen sensor 2 on T7 M98-99. The test shall nevertheless make and evaluation of the exhaust system back pressure.
This bulletin can be used if catalytic converter damage is suspected.
Possible primary faults:
The result of the testing will be one of the following:
In the event of high back pressure: ensure that the fault is not further back in the exhaust system. If not, replace catalytic converter.
In the case of customer complaint and if the car is within the warranty period, use the following information to fill out the claim: