Faulty transmission fluid pressure sensor/switch 'E'; Open or shorted wiring in the sensor circuit; Corroded or loose electrical connector at the sensor; Low transmission fluid level or contaminated fluid; Internal transmission mechanical issue causing abnormal pressure; Faulty transmission control module (TCM) or powertrain control module (PCM)

DTC codes / P09xx · Transmission / P0990

P0990Transmission Fluid Pressure Sensor/Switch 'E' Circuit High

Q: What does code P0990 mean?

Transmission Fluid Pressure Sensor/Switch 'E' Circuit High. P0990 indicates that the transmission control module (TCM) has detected an abnormally high voltage on the circuit for transmission fluid pressure sensor or switch 'E'. This sensor monitors hydraulic pressure inside the transmission, and a high signal typically means the circuit is open, shorted to voltage, or the sensor itself has failed.

P0990 indicates that the transmission control module (TCM) has detected an abnormally high voltage on the circuit for transmission fluid pressure sensor or switch 'E'. This sensor monitors hydraulic pressure inside the transmission, and a high signal typically means the circuit is open, shorted to voltage, or the sensor itself has failed.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illumination of the check engine light or transmission warning light
Harsh or delayed gear shifts
Transmission may enter limp mode (stuck in one gear)
Slipping or flaring during acceleration
Often no symptoms besides the warning light

Common causes, most likely first

Faulty transmission fluid pressure sensor/switch 'E'
Open or shorted wiring in the sensor circuit
Corroded or loose electrical connector at the sensor
Low transmission fluid level or contaminated fluid
Internal transmission mechanical issue causing abnormal pressure
Faulty transmission control module (TCM) or powertrain control module (PCM)

How to diagnose and fix it

Check transmission fluid level and condition; top off or replace fluid if needed
Inspect the sensor and its connector for damage, corrosion, or loose pins
Perform a voltage drop test on the sensor circuit to check for opens or shorts
Test the sensor with a multimeter according to manufacturer specifications
Replace the sensor/switch 'E' if it fails testing
Repair or replace damaged wiring or connectors
Clear the code and perform a road test to verify the repair

Don't overlook the simple checks first

A low transmission fluid level can cause pressure fluctuations that mimic a sensor failure, so always verify fluid level and condition before condemning the sensor.
Corroded connectors are a frequent culprit, especially in areas with road salt or high humidity, and can cause high voltage readings without any sensor fault.
The code may set intermittently due to a loose ground connection, so inspect and clean ground points related to the transmission.
Replacing the sensor without checking the circuit can lead to a repeat failure if the underlying wiring issue is not addressed.
Some vehicles use a pressure switch instead of a sensor, and a stuck-open switch can produce the same high voltage code.

Can I keep driving with P0990?

It is generally safe to drive with this code, but avoid aggressive acceleration or heavy loads because the transmission may shift erratically or enter limp mode. Have the vehicle diagnosed soon to prevent potential transmission damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.