Fault Code 0641

Fault code 0641

This fault is set when the ATF fluid in the torque converter reaches or exceeds 170 °C. The Tiptronic control unit sends a signal to limit the torque to 150 Nm.

ATF temperature

NOTE: The ignition must be switched off and then switched on again in order to display a fault indication in the instrument cluster.

Use the 'Actual values' menu in the Porsche System Tester II No. 9588 to check the transmission status and the actual values of the shift solenoid valves and sensors.

Diagnostic conditions

NOTE:
The ATF fluid level in the transmission must be OK and the specified ATF fluid must be used. The ATF filter and cooler must not be blocked.
- Ignition on
- Internal Tiptronic control unit function test
- Engine running, gear engaged and drive the vehicle
- No electrical fault (ATF temperature sensor) stored in fault memory
- Torque converter lockup clutch 'OFF'
- Output shaft speed < 800 rpm

Possible causes of fault
- 'Above upper limit', fault displayed in instrument cluster. Coolant shut-off valve faulty or does not switch. Cooler blocked, torque converter or transmission mechanical fault. Tiptronic control unit faulty.

Affected pins
Tiptronic control unit plug:
- Pin 8 'ATF temperature sensor ground', to existing transmission wiring plug 'pin B2'
- Pin 45 'ATF temperature sensor voltage/current', to existing transmission wiring plug 'pin B1'

Diagnosis/troubleshooting G 0210

Wiring diagram of ATF temperature sensor






1 - Tiptronic control unit
2 - ATF temperature sensor
8 - Pin (8)
45 - Pin (45)
I - ATF temperature sensor current flow

Data on ATF temperature sensor
- Sensor type: Thermistor
- Current input at 145 °C: 2 mA
- Internal resistance at -30 °C: 44 ± 6.6 kOhms
- Internal resistance at 10 °C: 6,445 ± 0.645 kOhms
- Internal resistance at 110 °C: 247 ± 16 Ohms
- Internal resistance at 145 °C: 111 ± 6 Ohms

NOTE:
Visual inspection: In the next troubleshooting section, please check first that the affected 'pins' on the Tiptronic control unit plug connection and the 'pins' on the 'existing transmission wiring' plug connection are neither damaged nor corroded. Remove any soiling or corrosion/oxidation. Replace damaged parts/wires.

NOTE:
Control unit replacement: Before replacing the 'Tiptronic control unit', the ground connections, power supply and plug connections on the control unit must be checked as OK. Please observe the coding of the control unit. After the test drive, read out the fault memory again with the Porsche System Tester II No. 9588. Additional causes of faults that could damage the 'Tiptronic control unit' should be detected and remedied.

DANGER:
Danger of burns from hot ATF fluid.
Skin or clothing may burn following contact with hot ATF fluid.
- Always allow ATF fluid to cool before draining.
- Wear suitable protective clothing.
- Use a suitable collecting container.