P0840

Fault code P0840

Oil pressure switch 1, transmission [Transmission Fluid Pressure Sensor/Switch 'A' Circuit]

NOTE: The ignition must be switched off and then switched on again in order to display an error message in the instrument cluster.

NOTE: This fault indicates that the solenoid/control valves in the hydraulic pressure circuit of 'oil pressure switch 1' keep jamming/sticking, or that 'transmission oil pressure switch 1' keeps jamming/sticking.

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'
- No electrical faults stored

1. 'Shift solenoid valve C1 (modulation pressure) or oil pressure switch 1' jams/sticks, selector lever in position 'D' and gear 5 or 6 engaged:
- Oil pressure switch 1 signal comes 'ON' 12 times and stays on for more than one second
- Temperature of ATF fluid '>= 20 °C'
- Line pressure '>= 6.0 bar'

Possible causes of fault
- 'Mechanical fault', 'oil pressure switch 1' signal stays 'ON' for more than one second. The Tiptronic control module carried out an electrical check on the electrical wires and oil pressure switch 1 and found them to be OK. Oil pressure switch 1 jams/ sticks mechanically.
- 'Mechanical fault', 'oil pressure switch 1' signal stays 'ON' for more than one second. The Tiptronic control module carried out an electrical check on the electrical wires and oil pressure switch 1 and found them to be OK. The 'shift solenoid valve C1 (modulation pressure)' jams/sticks mechanically.

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.