Tire Monitor System - Diagnostics
44 08 062016456/2
November 4, 2008. Supersedes Technical Service Bulletin Group 44 number 07-02 dated November 29, 2007 for reasons listed below.
Vehicle Information
44 TPMS diagnosis - allroad (C5) & A8/S8 (D2)
Condition
Helpful information for diagnosing BERU analog tire pressure monitoring systems installed in allroad (C5) and A8/S8 (D2) models.
Technical Background
A tire pressure monitoring warning displayed in the instrument cluster does not necessarily mean that there is a fault. It could mean that the pressure in one or more tires is low, the pressure in one or more tires needs to be adjusted, or the proper procedure for correcting low pressure or changing wheel sets was not followed.
Production Solution
Not applicable.
Service
Always explain to the customer that when TPMS warnings are displayed, it is important to first check all tire pressures and make any necessary adjustments as soon as possible. Description of the warning can be found in the Owner's Manual and should be referenced to distinguish between types of warnings. This is critical in order to properly diagnose TPMS concerns.
1. Before performing any diagnosis or replacing any parts, check and verify the following points with the customer.
a. Are all tire pressures accurate?
- Tires on one axle (2 front wheels or 2 rear wheels) should not have more than 6 psi (0.4 bar) of difference in pressure.
- Tire pressures should only be set when tires are cold or are at ambient temperature. Tire pressures stored when tires are hot/warm will drop after tires have cooled and may drop below the minimum threshold (based on the 4th digit in the coding), which will trigger a warning. On average, a temperature change of 10 degree F results in a pressure change of 1psi or a temperature change of 10 degree Cresults in a pressure change of 0.1bar.
b. Have any of the following been done without selecting Store pressures?
- Tire pressures adjusted (up or down).
- New sensor(s) installed.
- Tire rotation - system must learn new location of each sensor.
- Spare tire was used on A8/S8 models as a result of a flat tire.
c. Has the customer selected Store pressures but not carried out the required drive?
d. Is any aftermarket equipment, which operates on the same frequency of 315 MHz as the TPMS, used in the vehicle?
e. Were there any loose sensors in the vehicle or near the vehicle when Store pressures was selected and the required test drive was performed? If the system sees more sensors than it should based on the 3rd digit in the coding, it will set a DTC and will not store new pressures or learn any sensors.
Proceed to steps 2 & 3 only if none of the points in step 1 resolved the concern.
2. Check control unit coding.
- 1st digit: Identifies the vehicle manufacturer. Use 2 for Audi.
- 2nd digit: All vehicles are coded 2 by the factory. Code 0 is only used when a control unit is replaced.
- 3rd digit: This digit identifies how many antennas are used and how many wheels are monitored. For allroad, select 3, and for A8/S8, select 1. Both models have 4 antennas but allroad models do not have a sensor in the spare wheel. The spare wheel in A8/S8 models does not have its own antenna and is not monitored like other wheels. But it is received by one of the rear antennas and can be checked with a scan tool.
- 4th digit: Target pressure partially loaded. Check the tire pressure decal on the vehicle for proper pressure value. If the tire pressure is below or falls below this value, the system will not accept the Store pressures command and will issue a warning. Always store tire pressures when tires are cold or at ambient temperature.
- 5th digit: Target pressure fully loaded. Check the tire pressure decal on the vehicle for proper pressure value.
3. Check sensor and battery status of each sensor. MVBs 13-15 are only valid for A8/S8 models with a full size spare.
Sensor status - MVBs 3, 6, 9, 12, 15
- 01h: No changes in the actual pressure. Information is transmitted in normal mode.
- 02h: Tire pressure is dropping, has dropped, or increased rapidly by at least 3 psi (0.2 bar). Information is transmitted in high-speed mode.
- 03h: Thermal cut out. This indicates that a high temperature was detected. This can be caused by an under-inflated tire.
- e 04h: Sensor is inoperative and must be replaced.
Battery voltage - MVBs 3, 6, 9, 12, 15
- UB. iO: indicates OK
- UB. niO: indicates not OK
- kein Signal: indicates a loss of signal. This may be due to an intermittent loss and does not always indicate that communication is permanently lost.
Remaining sensor-battery life - MVBs 2, 5, 8, 11, 14
Battery service life is a theoretical value that is determined by special calculations. Difference in battery service life between sensors is not an issue and will not trigger a warning.
Only proceed to step 4 if all previous points have been addressed.
4. Check MVB 16, which cycles through all visible sensors. Allroad models must show 4 different sensor IDs, and A8/S8 models must show 5 different sensor IDs (with spare wheel).
Perform aerial diagnosis if not enough sensor are seen in MVB 16.
a. Select Vehicle Self Diagnosis >> 65 - Tire Pressure Monitoring >> Adaptation >> Channel 17 >> input 00001.
b. Next, check MVB 21 and wait until END is displayed, which indicates that the aerial diagnosis is complete.
c. Now check and address any DTCs in the TPMS control unit.
5. Check each sensor if antennas are okay after step 4 was completed. Release approximately 6 psi (0.4 bar) out of a tire and check its status in MVB 16, which should change to 02h (pressure loss recognition). Perform this step for all sensors. A sensor with a status that does not change to 02h is inoperative and should be replaced.
These are some additional points and alternative repairs, which may help with diagnosis.
6. On allroad vehicles, check the red connector (T6at) located in the left front A-pillar. It may be necessary to remove the plug and inspect all of the wires for proper connection.
7. If HF-wires, which connect the TPMS control unit to each antenna, are damaged they must not be repaired. Complete TPMS harness has to be replaced.
8. Keep in mind that new sensors will only function once they have been subjected to pressure above 22 psi (1.5 bar) for longer than 3 minutes.
9. Another way to isolate an inoperative sensor is to release 6 psi (0.4 bar) out of each tire while observing MVB 16. Then swap the wheel that has a sensor status that did not change with a wheel that has a sensor status that did change to 02h. Again release 6 psi (0.4 bar) out of these two tires and check their status. If the status still does not change on the suspected wheel, then this sensor is inoperative and must be replaced. If the sensor status does change but now the known good sensor does not change status to 02h, then this is not due to an inoperative sensor.
10. Check system status in MVB 19 after all diagnosis and/or repairs have been completed.
- 00263: Store pressures has been selected and system is ready to calibrate
- 002565: Store pressures has been selected and calibration is in progress
- 63535: System has learned all of its sensors (sensor positions and pressures). If this status is not reached after Store pressures was selected and a 30 minutes drive was carried out, it may be necessary to repeat some of the previous steps.
- 00015: Ignition key has been cycled (ON/OFF).
Warranty
This TSB is informational only and not applicable to any Audi warranty.
Required Parts and Tools
Not applicable.
Additional Information
More information on this system can be found in the following resources:
- Owners Manual
- ElsaWeb
- TSB 2011983
- SSP: 499 339 and 992 203
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.