Technical Service Bulletin # 901238
Instruments - Incorrect Outside Ambient Temperature Display
90 Outside air temperature reading: General Information
90 12 38
2032113/1
December 7, 2012.
Affected Vehicles
Date: 121207Audi A8L Quattro Sedan (4E8) V8-4.2L (BVJ)
Page 273
Condition
The customer may state that the outside ambient temperature display is incorrect.
Technical Background
To achieve a smoothening effect of the displayed outside ambient temperature, the value shown does not instantaneously follow the
temperature sensor measurement. The display will not change faster than 4?F (2?C) per minute. This concept applies to both falling and
rising temperatures.
A programming strategy is also implemented to avoid incorrect readings on a parked vehicle, due to the temperature sensor being
affected by outside influences such as radiant heat from the engine bay, elevated road surface temperatures, etc. Incorrect readings are
avoided through the following logic:
^ After switching the ignition on, temperature changes are only shown after 30 seconds for a stationary vehicle (vehicle speed = zero
and engine switched off).
^ Only when the vehicle drives faster than 12 mph (20 km/h), rising temperature values are displayed during the first 3 miles (5 km).
^
If the measured ambient temperature is above the displayed value, but falling, the display is not changed.
^ When the coolant temperature reaches 104?F (40?C) and the speed drops to under 12 mph (20 km/h), only falling ambient
temperature values are shown. For example, in stop and go traffic when the vehicle is often below 12 mph (20 km/h), it can take
some time before the displayed temperature is correct.
^ If conditions above are noted during these typical driving scenarios, the sensor is not at fault and does not need to be replaced.
Production Solution
Not Applicable
Service
Explain the operation to the customer.
Warranty
This TSB is informational only and not applicable to any Audi warranty.
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and
service manuals for the latest information.
Instruments - Incorrect Outside Ambient Temperature Display
90 Outside air temperature reading: General Information
90 12 38
2032113/1
December 7, 2012.
Affected Vehicles
Date: 121207Audi A8L Quattro Sedan (4E8) V8-4.2L (BVJ)
Page 273
Condition
The customer may state that the outside ambient temperature display is incorrect.
Technical Background
To achieve a smoothening effect of the displayed outside ambient temperature, the value shown does not instantaneously follow the
temperature sensor measurement. The display will not change faster than 4?F (2?C) per minute. This concept applies to both falling and
rising temperatures.
A programming strategy is also implemented to avoid incorrect readings on a parked vehicle, due to the temperature sensor being
affected by outside influences such as radiant heat from the engine bay, elevated road surface temperatures, etc. Incorrect readings are
avoided through the following logic:
^ After switching the ignition on, temperature changes are only shown after 30 seconds for a stationary vehicle (vehicle speed = zero
and engine switched off).
^ Only when the vehicle drives faster than 12 mph (20 km/h), rising temperature values are displayed during the first 3 miles (5 km).
^
If the measured ambient temperature is above the displayed value, but falling, the display is not changed.
^ When the coolant temperature reaches 104?F (40?C) and the speed drops to under 12 mph (20 km/h), only falling ambient
temperature values are shown. For example, in stop and go traffic when the vehicle is often below 12 mph (20 km/h), it can take
some time before the displayed temperature is correct.
^ If conditions above are noted during these typical driving scenarios, the sensor is not at fault and does not need to be replaced.
Production Solution
Not Applicable
Service
Explain the operation to the customer.
Warranty
This TSB is informational only and not applicable to any Audi warranty.
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and
service manuals for the latest information.
