OBD Guide

P1909

Transmission Temperature Sensor Circuit Open or Shorted to Power Or Ground

P1909 is an OBD-II diagnostic trouble code meaning: Transmission Temperature Sensor Circuit Open or Shorted to Power Or Ground. Common causes: broken wires to the temperature sensor, short circuit in the sensor circuit. Estimated repair cost: $17–67.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$17–67 (est.)

Symptoms

  • Emergency mode of automatic transmission (fixed gears)
  • Unstable gear shifting
  • The Check Engine light comes on
  • Floating engine speed
  • No transmission temperature reading on dashboard

Causes

  • Broken wires to the temperature sensor
  • Short circuit in the sensor circuit
  • Malfunction of the temperature sensor itself
  • Damage to the sensor connector
  • Problems with the automatic transmission control unit

How to Fix

  1. Check the integrity of the wiring to the sensor
  2. Measure the sensor resistance (compare with the nominal value)
  3. Check the voltage in the sensor circuit
  4. Inspect the connector for oxidation or damage.
  5. If necessary, replace the automatic transmission temperature sensor

Related codes

FAQ

What does the P1909 code mean?

P1909 is an OBD-II diagnostic trouble code that indicates: Transmission Temperature Sensor Circuit Open or Shorted to Power Or Ground

What causes a P1909 error code?

The most common causes of P1909 include: Broken wires to the temperature sensor; Short circuit in the sensor circuit; Malfunction of the temperature sensor itself; Damage to the sensor connector.

How do I fix a P1909 diagnostic trouble code?

To fix P1909: Check the integrity of the wiring to the sensor. Measure the sensor resistance (compare with the nominal value). Check the voltage in the sensor circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1909?

Limited driving only, diagnose soon

How much does it cost to fix P1909?

The estimated repair cost for P1909 is $17–67. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat