P1909 Code - Transmission Temperature Sensor Circuit Open or Shorted to Power Or Ground
Quick Answer
The P1909 diagnostic trouble code (DTC) indicates that there is a problem with the transmission temperature sensor circuit. Common causes include Faulty Temperature Sensor: The most common cause of this DTC is a faulty transmission temperature sensor, Wiring Issues: Damage or corrosion to the wiring harness connecting the sensor to the vehicle's computer can also trigger this code, Shorted Circuit: A shorted circuit between the sensor and power or ground can cause the transmission temperature sensor circuit to malfunction. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P1909 indicates Transmission Temperature Sensor Circuit Open or Shorted to Power Or Ground.
- Common causes
- Common causes include Faulty Temperature Sensor: The most common cause of this DTC is a faulty transmission temperature sensor, Wiring Issues: Damage or corrosion to the wiring harness connecting the sensor to the vehicle's computer can also trigger this code, Shorted Circuit: A shorted circuit between the sensor and power or ground can cause the transmission temperature sensor circuit to malfunction.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code P1909 Description
The P1909 diagnostic trouble code (DTC) indicates that there is a problem with the transmission temperature sensor circuit. This could mean that the circuit is open or shorted to power or ground, preventing the sensor from accurately measuring the transmission fluid temperature. The transmission temperature sensor is a crucial component in modern vehicles as it helps monitor the temperature of the transmission fluid, ensuring that it stays within the optimal operating range.
Common Causes of P1909
- Faulty Temperature Sensor: The most common cause of this DTC is a faulty transmission temperature sensor.
- Wiring Issues: Damage or corrosion to the wiring harness connecting the sensor to the vehicle's computer can also trigger this code.
- Shorted Circuit: A shorted circuit between the sensor and power or ground can cause the transmission temperature sensor circuit to malfunction.
- Loose Connections: Loose connections at the sensor or the vehicle's computer can disrupt the transmission temperature sensor's operation.
Symptoms of P1909
- Check Engine Light: The most common symptom associated with this DTC is the illumination of the check engine light on the dashboard.
- Transmission Overheating: If the transmission temperature sensor is not functioning properly, it may result in the transmission overheating, leading to erratic shifting or slipping.
- Reduced Fuel Efficiency: Incorrect transmission temperature readings can impact the vehicle's fuel efficiency, causing it to consume more fuel than usual.
- Harsh Shifting: A faulty transmission temperature sensor can cause the transmission to shift harshly or unpredictably.
How to Fix P1909
- Diagnose the Issue: Use a scan tool to retrieve the DTC and perform a visual inspection of the wiring harness and sensor connections.
- Test the Sensor: Check the transmission temperature sensor's resistance and voltage to determine if it is functioning correctly.
- Repair or Replace Wiring: Repair any damaged wiring or replace the wiring harness if necessary.
- Replace the Sensor: If the transmission temperature sensor is faulty, replace it with a new one.
- Clear the DTC: After completing the repair, clear the DTC using a scan tool to reset the check engine light.
Cost to Fix P1909
The cost of repairing a transmission temperature sensor circuit issue can vary depending on the extent of the damage and whether any parts need to be replaced. Typically, the cost of replacing the transmission temperature sensor itself ranges from $50 to $150, while the cost of labor can range from $100 to $200. Additional costs may be incurred if wiring or other components need to be replaced. It's recommended to consult with a qualified mechanic or repair shop for a more accurate cost estimate based on your specific vehicle and location.
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Code P1909 Information for Specific Makes
- P1909 Audi — Data Bus ECM 1/2 No Signal From ECM
- P1909 Ford — Transmission Temperature Sensor Circuit Open or Shorted to Power Or Ground
- P1909 Volkswagen — Transmission Temperature Sensor Circuit Open or Shorted to Power Or Ground
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