What does it mean?
Modern transmissions use transmission fluid pressure beyond just changing gears. Shifts between gears can be made more aggressively or smoothly depending on the driver’s habits. These adaptive shifts are also controlled with transmission fluid pressure by switches inside the transmission. Each adaptive pressure switch controls the harshness of gear changes in a predetermined set of gears which can vary depending on the manufacturer.
Typically, transmission fluid pressure sensor E, or TFP sensor E will control higher range shift points such as 4-5-6 shifts. These TFP sensors are integrated into control solenoid valve assemblies in many cases, though it’s possible that TFP sensors are loated on the valve body as well. TFP sensor E has an internal case ground and its normal position is closed, or low. The transmission control module (TCM) supplies a signal circuit to the TFP sensor E.
When oil pressure is present at TFP sensor E, the switch is open or high. The sensor signal is used to help the TCM control the clutch regulator valve for the gears it controls, adapting the transmission shifts to the TCM’s logic according to learned driver behaviors. DTC P0990 will set if the signal circuit to the TFP sensor E has high resistance as determined by the TCM.
DTC P0990 will set under certain conditions: The engine must be running Ignition voltage needs to be greater than 9.0 volts Transmission fluid temperature must be within -7C and +110C The TCM counts 30 instances of failure