The P0990 trouble code is a diagnostic trouble code (DTC) that indicates a problem with the Transmission Fluid Pressure Sensor/Switch “E” Circuit. This code is triggered when the Powertrain Control Module (PCM) detects an abnormal voltage signal from the transmission fluid pressure sensor, which can lead to various transmission issues. Understanding this code is crucial for vehicle owners and DIY mechanics, as it can affect the vehicle’s performance and drivability.
| P0990 Code Meaning | P0990 Code Common Causes |
|---|---|
| Transmission Fluid Pressure Sensor/Switch “E” Circuit High | Short circuit in the signal circuit |
| Indicates high voltage from the transmission fluid pressure sensor | Open ground circuit to the sensor |
| Potential issues with transmission control module (TCM) | Failed transmission fluid pressure sensor |
| May lead to poor shifting or limp mode operation | Corroded or damaged wiring connections |
Symptoms of P0990 Code
When the P0990 code is triggered, drivers may experience several symptoms, including:
- Malfunction Indicator Light (MIL): The check engine light will illuminate on the dashboard.
- Poor Shift Quality: Drivers may notice rough or erratic shifting between gears.
- Limp Mode Activation: The vehicle may start in a higher gear (like 2nd or 3rd) to prevent further damage, limiting speed and performance.
- Transmission Slippage: The transmission may slip or fail to engage properly, leading to decreased power.
Technical Explanations
The P0990 code relates specifically to the Transmission Fluid Pressure Sensor/Switch “E,” which monitors the hydraulic pressure within the transmission. This sensor provides critical data to the TCM, allowing it to adjust shifting patterns based on fluid pressure. When the PCM detects a voltage reading that is higher than expected from this sensor, it triggers the P0990 code.
Understanding Transmission Fluid Pressure Sensor
The Transmission Fluid Pressure Sensor is vital for ensuring that the transmission operates efficiently. It measures the pressure of the fluid and sends this information to the TCM. A malfunctioning sensor can lead to incorrect shifting and potential damage to the transmission.
Step-by-Step Diagnosis
Diagnosing a P0990 code involves several steps:
- Initial Inspection: Start by checking for any additional trouble codes that may be related. Use an OBD-II scanner to retrieve all stored codes.
- Visual Inspection: Locate the Transmission Fluid Pressure Sensor and inspect its wiring and connectors for signs of damage, corrosion, or loose connections.
- Check Transmission Fluid Level: Ensure that the transmission fluid is at the correct level and in good condition. Contaminated or low fluid can cause erroneous readings.
- Voltage Testing: Using a digital voltmeter, check the voltage at the sensor connector with the ignition on but engine off. Compare this reading with manufacturer specifications.
- Resistance Testing: Measure resistance across the sensor terminals with an ohmmeter while wiggling the connector. Inconsistent readings may indicate a faulty sensor.
- Clear Codes: After performing these checks, clear any codes from memory and see if P0990 returns after a test drive.
Solution Methods
To resolve a P0990 trouble code, consider these solutions:
- Repair Wiring Issues: If any damaged wiring or connectors are found during inspection, repair or replace them as necessary.
- Replace Transmission Fluid Pressure Sensor: If testing indicates that the sensor is faulty, replacing it is often necessary.
- Check TCM Functionality: If problems persist after replacing the sensor, further diagnosis of the TCM may be required, as it could also be malfunctioning.
- Fluid Replacement: If transmission fluid is contaminated or low, replace it according to manufacturer recommendations.
Cost Estimates
The costs associated with diagnosing and repairing a P0990 code can vary widely based on location and vehicle type:
- Diagnostic Fee: Expect to pay between $75 and $150 for a professional diagnostic service.
- Transmission Fluid Replacement: This typically ranges from $100 to $200 depending on fluid type and labor costs.
- Sensor Replacement: The cost of a new Transmission Fluid Pressure Sensor can range from $50 to $150 for parts alone, with labor adding another $100-$200.
Warnings and Recommendations
- Professional Help Recommended: If you are not comfortable performing these diagnostics or repairs yourself, it is advisable to seek professional assistance to avoid further damage.
- Regular Maintenance: Regularly check your transmission fluid levels and quality as part of routine vehicle maintenance to prevent issues like P0990 from occurring in the first place.
- Avoid Driving in Limp Mode: If your vehicle enters limp mode due to this code, avoid driving it until repairs are made as this can cause additional strain on your transmission.
Frequently Asked Questions About P0990
- What does P0990 mean?
The P0990 code indicates a high voltage condition in the Transmission Fluid Pressure Sensor/Switch “E” circuit. - What are common symptoms of P0990?
Common symptoms include poor shift quality, limp mode activation, and illumination of the check engine light. - How serious is a P0990 code?
This code can lead to significant transmission issues if not addressed promptly; it’s advisable to diagnose it immediately. - Can I drive my car with a P0990 code?
While you may be able to drive short distances, it’s not recommended as it can cause further damage. - How do I fix a P0990 code?
Fixing this code typically involves inspecting wiring, replacing faulty sensors, and ensuring proper transmission fluid levels. - What tools do I need for diagnosis?
A digital voltmeter, an ohmmeter, and an OBD-II scanner are essential tools for diagnosing this trouble code. - Is professional help necessary for P0990?
If you’re unsure about performing diagnostics or repairs yourself, it’s best to consult with a qualified mechanic. - How much will it cost to fix a P0990?
The total cost can range from $250 to over $500 depending on repairs needed and labor costs.
In conclusion, understanding and addressing trouble codes like P0990 is essential for maintaining your vehicle’s health. By following proper diagnostic steps and solutions outlined above, vehicle owners and DIY mechanics can effectively tackle this issue. Regular maintenance and prompt attention to warning signs will help ensure your vehicle runs smoothly for years to come.