The P0990 trouble code indicates an issue with the Transmission Fluid Pressure Sensor/Switch ‘E’ Circuit, specifically that the circuit is reading a high voltage. This code is part of the On-Board Diagnostics II (OBD-II) system, which monitors various components of the vehicle’s powertrain, including the engine and transmission. When this code is triggered, it suggests that the vehicle’s powertrain control module (PCM) has detected an abnormal condition in the transmission fluid pressure sensor circuit. Ignoring this code can lead to significant transmission issues, so it’s essential for vehicle owners and DIY mechanics to understand its implications and how to address it.
| P0990 Code Meaning | P0990 Code Common Causes |
|---|---|
| Transmission Fluid Pressure Sensor/Switch ‘E’ Circuit High | Short to power in the signal circuit |
| Indicates a malfunction in the transmission fluid pressure sensor circuit | Open ground circuit to the sensor |
| Potential impact on transmission shifting and performance | Failed Transmission Fluid Pressure Sensor (TFPS) |
| Faulty Powertrain Control Module (PCM) |
Symptoms of P0990 Code
When a P0990 code is present, drivers may notice several symptoms that indicate a problem with their vehicle’s transmission system. Common symptoms include:
- Malfunction Indicator Light (MIL): The check engine light may illuminate on the dashboard.
- Change in Shift Quality: Drivers might experience harsh or erratic shifting as the PCM attempts to compensate for incorrect pressure readings.
- Limp Mode Activation: The vehicle may start in second or third gear, limiting performance to protect the transmission.
Technical Explanation
The Transmission Fluid Pressure Sensor (TFPS) measures the hydraulic pressure within the transmission. This information is critical for the PCM to manage shifting and ensure optimal performance. When the P0990 code is triggered, it usually indicates that there is a high voltage signal being sent from the TFPS to the PCM, which can be caused by electrical faults or sensor malfunctions.
Step-by-Step Diagnosis
Diagnosing a P0990 code involves several steps:
- Initial Scan: Use an OBD-II scanner to confirm that P0990 is present and check for any related codes that could provide additional context.
- Visual Inspection: Inspect wiring and connectors associated with the TFPS for any signs of damage, corrosion, or loose connections.
- Electrical Testing:
- Disconnect the TFPS connector.
- Using a digital voltmeter, measure voltage at the connector while turning on the ignition (engine off). The reading should align with manufacturer specifications (typically 5V or 12V).
- If readings are incorrect, trace back through wiring for shorts or opens.
- Resistance Testing:
- With the connector still disconnected, use an ohmmeter to measure resistance across the TFPS terminals.
- Compare readings against specifications; if outside range, replace the sensor.
- Clear Codes and Test Drive: After repairs, clear any stored codes and take the vehicle for a test drive to see if P0990 reappears.
Solution Methods
To resolve a P0990 code effectively, consider these solutions:
- Repair Wiring Issues: If damaged wiring or corroded connectors are found, repair or replace them as necessary.
- Replace TFPS: If testing indicates that the TFPS is faulty, replacing it will likely resolve the issue.
- Check PCM/TCM: If all other components are functioning correctly but the code persists, consider testing or replacing the Powertrain Control Module (PCM) or Transmission Control Module (TCM).
Cost Estimates
The costs associated with diagnosing and repairing a P0990 code can vary widely depending on labor rates and parts prices:
- Diagnostic Fees: $100 – $150 for professional diagnostics.
- Transmission Fluid Pressure Sensor Replacement: $50 – $200 for parts; labor costs can add another $100 – $150.
- Wiring Repairs: Costs depend on extent of damage but typically range from $50 – $300.
Warnings and Recommendations
- Professional Help: If you are unsure about any step in diagnosing or repairing this issue, it is recommended to seek assistance from a qualified mechanic.
- Avoid Driving: Continuing to drive with a P0990 code can lead to further damage to your transmission system.
Closing Paragraph
Understanding and addressing a P0990 trouble code is crucial for maintaining your vehicle’s performance and longevity. By following systematic diagnostic procedures and being aware of potential symptoms and causes, vehicle owners can effectively troubleshoot this issue. Always prioritize safety and seek professional help when necessary to ensure your vehicle operates smoothly.
Frequently Asked Questions About P0990
- What does error code P0990 mean?
P0990 indicates that there is a high voltage reading from the Transmission Fluid Pressure Sensor/Switch ‘E’ circuit. - What are common symptoms of a P0990 code?
Common symptoms include a check engine light, erratic shifting, and limp mode activation. - How do I diagnose a P0990 trouble code?
Start by scanning for codes, visually inspecting wiring connections, testing voltage at the sensor connector, and checking resistance. - Can I drive my car with a P0990 code?
No, it’s advisable not to drive your vehicle as it may lead to further transmission damage. - What should I do if I get a P0990 code?
Inspect wiring and connectors first; if everything appears fine, consider replacing the Transmission Fluid Pressure Sensor. - How much does it cost to fix a P0990 code?
The total cost can range from $100 for diagnostics up to $500 or more depending on repairs needed. - Is it safe to replace parts myself?
If you have mechanical knowledge and tools, you can attempt repairs; otherwise, consult a professional. - What happens if I ignore a P0990 code?
Ignoring this code can lead to severe transmission problems and costly repairs down the line.