Faulty transmission fluid pressure sensor or switch 'E'; Damaged or corroded wiring harness or connector at the sensor; Open or shorted circuit in the signal or ground wire; Low transmission fluid level or degraded fluid causing incorrect pressure readings; Internal transmission mechanical issues affecting pressure; Faulty transmission control module (TCM) or poor electrical connections; Contamination or debris blocking the sensor port

DTC codes / P09xx · Transmission / P0989

P0989Transmission Fluid Pressure Sensor/Switch 'E' Circuit Low

Q: What does code P0989 mean?

Transmission Fluid Pressure Sensor/Switch 'E' Circuit Low. P0989 is a generic OBD-II code that indicates the transmission fluid pressure sensor or switch 'E' circuit is reporting a voltage lower than the manufacturer's expected range. The transmission control module (TCM) monitors this circuit to ensure the pressure sensor is functioning correctly, and it sets this code when the signal voltage stays below the calibrated threshold for a set period.

P0989 is a generic OBD-II code that indicates the transmission fluid pressure sensor or switch 'E' circuit is reporting a voltage lower than the manufacturer's expected range. The transmission control module (TCM) monitors this circuit to ensure the pressure sensor is functioning correctly, and it sets this code when the signal voltage stays below the calibrated threshold for a set period.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illumination of the check engine light or transmission warning light, often with no other symptoms
Harsh or delayed gear shifts as the transmission may default to a limp-home mode
Transmission may slip or fail to engage certain gears
Erratic shift points or torque converter clutch operation
Reduced fuel economy due to improper shift scheduling
In some cases, the vehicle may enter limp mode and limit speed

Common causes, most likely first

Faulty transmission fluid pressure sensor or switch 'E'
Damaged or corroded wiring harness or connector at the sensor
Open or shorted circuit in the signal or ground wire
Low transmission fluid level or degraded fluid causing incorrect pressure readings
Internal transmission mechanical issues affecting pressure
Faulty transmission control module (TCM) or poor electrical connections
Contamination or debris blocking the sensor port

How to diagnose and fix it

Check transmission fluid level and condition; top off or replace fluid if necessary
Inspect the sensor and its connector for damage, corrosion, or loose pins; clean and secure as needed
Perform a visual inspection of the wiring harness for chafing, breaks, or shorts
Use a multimeter to test the sensor's resistance and voltage output according to manufacturer specifications
Check the sensor's ground circuit for continuity and proper grounding
If the sensor fails testing, replace it and clear the code
If the code persists after sensor replacement, diagnose the TCM and internal transmission components

Don't overlook the fluid and wiring

A low transmission fluid level or degraded fluid can cause the pressure sensor to read out of range, setting P0989 even when the sensor itself is good.
Corroded or loose pins in the sensor connector are a frequent cause of low voltage codes and are often missed during a quick visual inspection.
The code may be set by a faulty ground connection rather than a failed sensor, so always verify the ground circuit before replacing parts.
On some vehicles, a failing transmission control module can mimic a sensor circuit fault, so module diagnostics should be performed if the sensor and wiring test good.
P0989 can be an intermittent code caused by vibration or heat affecting the wiring, so wiggle-test the harness while monitoring live data.

Can I keep driving with P0989?

If the vehicle is shifting normally and the only symptom is the warning light, you can drive cautiously to a repair shop, but avoid heavy loads or aggressive driving. If the transmission is slipping, shifting harshly, or entering limp mode, stop driving and have the vehicle towed to prevent further 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.