P0934 The transmission line pressure sensor circuit is sending too low a voltage

Hydraulic pressure sensor circuit low

P0934 in short

P0934 means the hydraulic (line) pressure sensor circuit in the transmission is sending a low voltage signal. A wiring short or open, a corroded connector, a failed pressure sensor, or rarely a control module fault can cause it. Kelley Blue Book says to stop driving and get expert help.

The transmission has a sensor that reports hydraulic line pressure to the computer. P0934 is set when that circuit's voltage is abnormally low, so the computer cannot tell what the real pressure is.

Both references list damaged wiring or a short to ground, a defective sensor, and corroded or loose connectors; Kelley Blue Book adds blown fuses and says PCM, ECM or TCM faults are rare. TroubleCodes.net says bulletins exist for some vehicles about over-sensitive sensor specifications; none was read for this code.

Drivability effects can be serious: harsh shifts at low rpm, delayed shifts, weak acceleration, high engine revs and limp mode with a fixed pressure setting. Kelley Blue Book rates it very serious; TroubleCodes.net rates it moderate.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Damaged wiring, short to ground or corroded connector

    Common general cause
    Why it ranks here
    Both references list wiring damage and connector faults first, and TroubleCodes.net's tests start with the harness and connector.
    What would change this
    Rises if the harness is chafed or the connector is wet, corroded or bent. Falls if the circuit tests good.

  2. Failed hydraulic pressure sensor

    Common general cause
    Why it ranks here
    Both references list a defective sensor, and TroubleCodes.net has the sensor disconnected and retested to find an internal short.
    What would change this
    Rises if the signal stays low with the sensor disconnected and the wiring good. Falls if the wiring is at fault.

  3. PCM, ECM or TCM fault

    Possible — needs testing
    Why it ranks here
    Kelley Blue Book calls these rare causes; they come only after the wiring and sensor test good.
    What would change this
    Rises if the 5-volt reference and ground are good, the sensor is good and the code returns. Falls otherwise.
    How to test the transmission control module (tcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all stored codes from the engine and transmission computers and note any other pressure or solenoid codes.

    Low riskTool: OBD-II scan tool

    • IfOther transmission codes are stored

      It meansDiagnose them together with P0934.

      Go to step 2

    • IfOnly P0934

      It meansInspect the wiring.

      Go to step 2

  2. Have a shop inspect the sensor harness for damage and the connector for water, corrosion or bent pins.

    Best left to a shopTool: flashlight, scan tool

    Warning:The transmission is hot after driving and fluid may drip from the connector area; do not unplug anything yourself.

  3. Measure the sensor's 5-volt reference, ground and signal, then disconnect the sensor and retest to separate a shorted sensor from a shorted wire.

    Best left to a shopTool: digital multimeter, scan tool

    Warning:Probing a live connector can short pins and damage the control module; leave this to a shop.

Symptoms

  • Check engine light
  • Harsh or delayed shifting Gets more serious: stop and have it checked.
  • Weak acceleration or high engine revs Gets more serious: stop and have it checked.
  • Limp mode or starting in second gear Gets more serious: stop and have it checked.

How to fix

  1. Ask a dealer or transmission shop whether your VIN has a bulletin for P0934 before replacing parts.

On your vehicle

We don't have reviewed vehicle-specific evidence for P0934 yet. The causes and tests above apply across vehicles.

All Transmission codes

P0934 questions

Is it safe to drive with P0934?

Kelley Blue Book says to stop driving and get expert help because of serious drivability problems and possible transmission damage. TroubleCodes.net rates it moderate.

Sources and review

  1. P0934 Code - Hydraulic Pressure Sensor Circuit Low — Kelley Blue Book
  2. P0934 - Hydraulic Pressure Sensor Circuit Low Input — TroubleCodes.net
Last reviewed
Written by
Saurabh K.
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