P0990 code definition

The P0990 code is a generic powertrain code related to the transmission, including pressure faults and sensor failures. In this case, the transmission control module has received a higher than normal voltage signal from the transmission fluid pressure sensor/switch E.

What the P0990 code means

A vehicle uses the transmission fluid pressure sensor to assist with changing gears. Adaptive shifts are controlled via transmission fluid pressure through switches. Each pressure switch will control how harsh or smooth a gear changes. Pressure sensors and related shift points vary by manufacturer, by traditionally the E transmission fluid pressure sensor correlates to higher shift points, including the 4-5-6 shifts. The pressure sensors are often integrated into the control solenoid valve assembly or at times on the valve body itself.

A code P0990 will be stored when the ECM or transmission control module has received a voltage reading from the E transmission fluid pressure sensor that is higher than predetermined manufacturer parameters. While each manufacturer varies, the P0990 code will typically not be stored until around 30 failures.

What causes the P0990 code?

Several problems may cause a P0990 code including:

  • Low transmission fluid
  • Dirty transmission fluid
  • Damaged or corroded wiring or related connectors and components
  • Damaged or defective transmission fluid pressure sensor
  • Damaged or defective transmission fluid pressure switch
  • Damaged or defective transmission control module
  • Damaged or defective ECM (rare)

What are the symptoms of the P0990 code?

Symptoms of a P0990 code may include:

  • Check engine or warning light may illuminate
  • There may be no symptoms for a P0990 other than a stored code
  • Vehicle may shift harshly or roughly
  • Vehicle may have delayed shifts into gear, especially the higher gears 4-5-6

How does a mechanic diagnose the P0990 code?

A mechanic may use several methods to diagnose a P0990 trouble code, including:

  • Utilize an OBD-II scanner to check for a stored P0990 trouble code
  • Check transmission fluid level
  • Check transmission fluid quality
  • If transmission fluid is off color or smells burned, check transmission pan for clutch debris or other contaminants, which may be a sign of more serious problems or transmission failure
  • Visually inspect wiring, connectors, and harnesses for signs of damage
  • Use a specialized scan tool to monitor the transmission fluid pressure sensors while shifting through each gear
  • Test the transmission fluid pressure sensor/switch E for continuity
  • Test the transmission control module

Common mistakes when diagnosing the P0990 code

One common mistake with any transmission-related fault code is neglecting to check the transmission fluid level and quality prior to making additional repairs. It is recommended to always start with the transmission fluid, as debris and contamination in the fluid could signal a larger problem, such as internal transmission failure.

How serious is the P0990 code?

Because a vehicle’s safe driving operation most likely will be impacted due to faults that store a P0990 code, this code is considered a potentially serious code. When this code appears, it is recommended to immediately take your vehicle to your local service center or mechanic for repair and diagnosis.

What repairs can fix the P0990 code?

Several repairs can fix a P0990 trouble code and include:

  • Fill transmission fluid to manufacturer recommended levels
  • Perform a transmission fluid service and flush, if necessary
  • Repair or replace damaged or corroded wiring and related electrical components
  • Repair or replace damaged or defective transmission fluid pressure sensor/switch E
  • Repair or replace damaged or defective transmission control module
  • Repair or replace damaged or defective ECM (rare)
  • Clear all codes, test-drive the vehicle, and rescan to see if any codes reappear

Additional comments related to a P0990 code

Scan tools may see transmission fluid pressure sensor/switch E as being sensor/switch 5. It is recommended to check your vehicle service manual for specifics.

Need help with a P0990 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

This article originally appeared on YourMechanic.com as P0990 OBD-II Trouble Code: Transmission Fluid Pressure Sensor/Switch E Circuit High and was authored by Parker Hill.


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