What it means
The control module detects a high electrical level in the transmission fluid pressure sensor/switch E circuit.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Transmission fluid pressure sensor/switch E supplies pressure feedback used by the control module to manage shifts. P0990 sets when the E circuit signal is higher than expected, which can be caused by a signal wire shorted to battery power, an open sensor, or a poor connector connection.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Save freeze-frame data and review pressure sensor/switch E live data to confirm whether the signal is high or fixed when the fault appears.
- Inspect the E sensor connector and harness for corrosion, loose terminals, open wires, or insulation damaged near a battery-positive feed.
- With the wiring diagram, test the signal wire for a short to battery power and check for an open between the sensor and module, isolating components as the manufacturer specifies.
- Check the E sensor's supply, ground, and output and compare them with the manufacturer's specification.
- If the circuit is intact but the signal remains high, test pressure sensor/switch E and consider a module fault only after sensor and wiring checks pass.
Common fixes
- Clean and secure the E sensor connector or replace damaged terminals.
- Repair a signal wire shorted to battery power or an open in the circuit.
- Replace pressure sensor/switch E if it is open or its output fails specification.
- Repair a verified control-module fault after the sensor and harness pass testing.
Can I keep driving?
Avoid towing and hard acceleration if the transmission shifts abnormally or slips; arrange prompt diagnosis and keep any trip short if it still shifts reliably. A high or invalid pressure signal can lead to poor shift control, and continued slipping can damage the transmission.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.