P0991 Code - Transmission Fluid Pressure Sensor/Switch 'E' Circuit Intermittent
Quick Answer
The P0991 diagnostic trouble code (DTC) indicates an intermittent issue with the Transmission Fluid Pressure Sensor/Switch 'E' circuit. Common causes include Faulty Transmission Fluid Pressure Sensor: The sensor itself may be malfunctioning, providing incorrect readings to the ECM/TCM, Wiring Issues: Damaged, frayed, or corroded wiring or connectors in the sensor circuit can disrupt the signal, Low or Contaminated Transmission Fluid: Insufficient fluid levels or dirty fluid can affect sensor performance and transmission operation. 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
- P0991 indicates Transmission Fluid Pressure Sensor/Switch 'E' Circuit Intermittent.
- Common causes
- Common causes include Faulty Transmission Fluid Pressure Sensor: The sensor itself may be malfunctioning, providing incorrect readings to the ECM/TCM, Wiring Issues: Damaged, frayed, or corroded wiring or connectors in the sensor circuit can disrupt the signal, Low or Contaminated Transmission Fluid: Insufficient fluid levels or dirty fluid can affect sensor performance and transmission operation.
- 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 P0991 Description
The P0991 diagnostic trouble code (DTC) indicates an intermittent issue with the Transmission Fluid Pressure Sensor/Switch 'E' circuit. This sensor plays a crucial role in monitoring the hydraulic pressure within the transmission system, providing real-time data to the vehicle's Engine Control Module (ECM) or Transmission Control Module (TCM). The ECM/TCM uses this information to optimize shifting patterns, ensuring smooth gear transitions and maintaining engine performance.
Common Causes of P0991
- Faulty Transmission Fluid Pressure Sensor: The sensor itself may be malfunctioning, providing incorrect readings to the ECM/TCM.
- Wiring Issues: Damaged, frayed, or corroded wiring or connectors in the sensor circuit can disrupt the signal.
- Low or Contaminated Transmission Fluid: Insufficient fluid levels or dirty fluid can affect sensor performance and transmission operation.
- Faulty ECM/TCM: A malfunctioning control module may misinterpret the sensor signals, leading to erratic behavior.
- Mechanical Transmission Issues: Internal transmission problems, such as worn components or valve body issues, can also trigger this code.
Symptoms of P0991
- Harsh or Erratic Shifting: The vehicle may experience rough or unexpected gear changes, which can affect drivability.
- Delayed Engagement: There may be a noticeable delay when shifting from park to drive or reverse.
- Transmission Slipping: The transmission may slip out of gear unexpectedly, leading to a loss of power.
- Warning Lights: The check engine light or transmission warning light may illuminate on the dashboard.
- Reduced Fuel Efficiency: Poor transmission performance can lead to increased fuel consumption.
How to Fix P0991
- Visual Inspection: Begin with a thorough inspection of the wiring and connectors associated with the transmission fluid pressure sensor for signs of damage or corrosion.
- Check Transmission Fluid: Verify the fluid level and condition. If the fluid is low or contaminated, it should be replaced, and any leaks should be addressed.
- Test the Sensor: Use a multimeter to test the resistance and voltage output of the transmission fluid pressure sensor to determine if it is functioning correctly.
- Repair or Replace Components: If the sensor is faulty, replace it. If wiring issues are found, repair or replace the damaged sections.
- Clear Codes and Test Drive: After repairs, clear the DTCs and perform a test drive to ensure the issue is resolved and the code does not reappear.
Cost to Fix P0991
The cost to repair a P0991 code can vary widely based on the specific issue identified. Generally, the cost for parts and labor can range from $150 to $600. For instance, a new transmission fluid pressure sensor may cost between $50 and $200, while labor costs can range from $80 to $150 per hour, depending on the shop's location and reputation. It is important to note that diagnosis time and labor rates can differ significantly based on factors such as vehicle make and model, engine type, and geographic location. In metropolitan areas or at dealerships, rates may be higher, while independent shops often offer more competitive pricing. For a precise estimate, it is advisable to consult local repair shops.
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Code P0991 Information for Specific Makes
- P0991 Dodge — Transmission Fluid Pressure Sensor/Switch 'E' Circuit Intermittent
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