P0988: Transmission Fluid Pressure Sensor/Switch E Circuit Range/Performance

What it means

The control module detects a range or performance problem 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 provides pressure feedback that the control module compares with expected transmission conditions. P0988 means the E circuit's reported performance is outside the expected range or does not respond as expected; the code does not by itself prove whether the cause is electrical, the sensor, or actual fluid pressure.

Common causes

Most likely first.

1. Faulty pressure sensor/switch E
2. Open, shorted, or high-resistance wiring or connection
3. Transmission fluid pressure outside the expected range
4. Control module fault

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

1. Save freeze-frame data and observe pressure sensor/switch E live data alongside commanded gear and operating conditions to identify when the reading goes out of range.
2. Inspect the E sensor connector and wiring for corrosion, loose pins, fluid contamination, opens, shorts, or chafing.
3. Check transmission fluid level and condition using the manufacturer's procedure, since abnormal fluid condition or level can accompany pressure problems.
4. Test the E sensor's reference, ground, and signal circuit, then compare its output and pressure response with the manufacturer's specification.
5. If the electrical circuit passes, have actual transmission pressure checked using the manufacturer's specified method before condemning the sensor or control module.

Common fixes

• Repair loose, corroded, or damaged E sensor wiring and connector terminals.
• Correct transmission fluid level or condition using the specified fluid and service procedure.
• Replace pressure sensor/switch E if its output fails the manufacturer's tests.
• Repair an internal hydraulic pressure problem if measured pressure is outside specification.
• Address a control-module fault only after the sensor, wiring, and pressure checks pass.

Can I keep driving?

Avoid towing, steep climbs, and hard acceleration if shifting is abnormal; use only a short, gentle trip for diagnosis if the transmission still engages reliably. Slipping or repeated harsh shifts can quickly add wear, so stop if drive is lost or the vehicle shifts unpredictably.