P0734
Fault code P0734Gear '4', incorrect ratio [Gear 4 Incorrect Ratio]
The target gear specified by the Tiptronic control module is compared with the current gear. This fault is set if the detected gear is not the same as the target gear. The detected gear is determined from: 'input shaft speed (turbine speed) inductive pickup - output shaft speed inductive pickup' x 'transmission ratio for gear 4'.
NOTE: The ignition must be switched off and then switched on again in order to display an error message in the instrument cluster.
System in limp-home mode 2: Fault caused by incorrect gear ratio or unusual switching.
NOTE: Please refer to 'Limp-home mode 2' table in the main chapter entitled 'Control module function (coding/programming)'.
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.
The following requirements are met for at least 0.5 seconds:
- Voltage greater than 10.2 V and less than 15.5 V
- Ignition on
- Internal Tiptronic control module function test was completed successfully
- Engine runs without malfunctions, engine speed '> 400 rpm'
- Temperature of ATF fluid > 20 °C
- Selector lever in position 'D' and gear 4 engaged
- No selector lever faults
- No speed faults in sensors: PSM, input shaft (turbine wheel), output shaft
- No electrical faults stored for shift solenoid valves and modulation pressure
- Output shaft speed >= 250 rpm
This fault is set after the following conditions have occurred 12 times:
- Calculated value in 'gear 1' is less than the default value for more than one second
- or: Calculated value in 'gear 4' is greater than the default value for more than one second
- or: Calculated value in 'gear 5' is less than the default value for more than one second
- or: Calculated value in 'gear 6' is less than the default value for more than one second
Possible causes of fault
NOTE:
There is a fault in the mechanical/hydraulic parts of the transmission.
- 'Mechanical fault', clutch or brake band faulty
- 'Mechanical fault', hydraulic control unit faulty
Affected pins
Tiptronic control module plug:
- Pin '-'
Diagnosis/troubleshooting G 0210
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.
