P1390 Code: Complete DIY Repair Guide

The P1390 trouble code is a diagnostic trouble code (DTC) that indicates a potential issue with the timing of the engine’s camshaft and crankshaft. Specifically, it suggests that the timing belt may have skipped one or more teeth, which can lead to serious engine performance problems. When this code appears, it often triggers the check engine light and can cause noticeable changes in vehicle performance, such as rough idling or stalling. Understanding this code is essential for vehicle owners and DIY mechanics to diagnose and resolve the underlying issues effectively.

Symptoms of P1390 Code

When the P1390 code is triggered, several symptoms may manifest, indicating that there is an issue with the timing system of the engine:

• Check Engine Light: The most common symptom is the illumination of the check engine light on the dashboard.
• Rough Idling: The engine may idle roughly or unevenly, causing vibrations felt throughout the vehicle.
• Stalling: In severe cases, the engine may stall unexpectedly, especially during acceleration or deceleration.
• Poor Acceleration: Drivers may notice a significant decrease in power and responsiveness when accelerating.
• Increased Emissions: The vehicle may produce higher emissions due to improper fuel combustion.

Technical Explanations

The P1390 code primarily relates to timing issues between the crankshaft and camshaft. The crankshaft position sensor monitors the position of the crankshaft and sends this information to the engine control unit (ECU). The camshaft position sensor performs a similar function for the camshaft. If these sensors detect a discrepancy in timing—often due to a skipped timing belt or chain—the ECU triggers the P1390 code.

Timing Belt Functionality

The timing belt synchronizes the rotation of the crankshaft and camshaft(s). If it skips a tooth, it can result in misalignment, leading to improper valve timing. This misalignment can cause severe engine damage if not addressed promptly.

Importance of Proper Installation

When replacing components like the timing belt or sensors, ensuring proper installation is crucial. Incorrect installation can lead to recurring issues and further complications down the line.

Step-by-Step Diagnosis

Diagnosing a P1390 code involves several steps:

1. Scan for Codes: Use an OBD-II scanner to confirm that P1390 is present and check for any additional codes that may provide more context.
2. Visual Inspection: Inspect the timing belt for signs of wear or damage. Ensure that it is properly aligned with all timing marks.
3. Check Sensors: Examine both the camshaft and crankshaft position sensors for proper connection and functionality.
4. Perform a Compression Test: Conduct a compression test on all cylinders to assess engine health. Low compression might indicate internal damage due to timing issues.
5. Relearn Procedures: If any components related to timing have been replaced, follow manufacturer-specific procedures for relearning sensor positions.

Solution Methods

Addressing a P1390 code typically involves one or more of the following solutions:

• Timing Belt Replacement: If the belt has skipped teeth or shows signs of wear, replace it along with any associated components (tensioners, pulleys).
• Sensor Replacement: If either sensor is faulty, replace it with an OEM part to ensure compatibility.
• Recheck Installation: Verify that all components are installed correctly according to manufacturer specifications.
• ECU Relearn Procedure: After repairs, perform an ECU relearn procedure if required by your vehicle’s manufacturer.

Cost Estimates

Costs can vary significantly based on vehicle make and model, as well as labor rates in your area:

• Timing Belt Replacement: $500 – $1,000 (including parts and labor)
• Sensor Replacement: $100 – $300 per sensor
• Diagnostic Fees: $75 – $150 at most repair shops

Warnings and Recommendations

• Professional Assistance: If you are not comfortable performing these diagnostics or repairs yourself, it is strongly recommended to seek help from a qualified mechanic.
• Avoid Driving with P1390 Code: Continuing to drive with this code can lead to severe engine damage.
• Follow Manufacturer Guidelines: Always refer to your vehicle’s service manual for specific instructions related to repairs and diagnostics.

Closing Paragraph

The P1390 trouble code signifies critical issues related to your vehicle’s timing system. By understanding its meaning and symptoms, you can take proactive steps toward diagnosing and resolving these issues effectively. Whether you choose to tackle this as a DIY project or seek professional help, addressing a P1390 code promptly will help maintain your vehicle’s performance and longevity.

Frequently Asked Questions About P1390

• What does the P1390 code mean?
  The P1390 code indicates that there is an issue with the timing system of your engine, often due to a skipped timing belt.
• Can I drive my car with a P1390 code?
  No, driving with this code can lead to severe engine damage; it’s advisable to address it immediately.
• How do I fix a P1390 code?
  Fixing this code typically involves inspecting and potentially replacing the timing belt or sensors related to camshaft and crankshaft positioning.
• What are common symptoms of a P1390 code?
  Common symptoms include rough idling, stalling, poor acceleration, and an illuminated check engine light.
• Is professional help necessary for fixing a P1390?
  If you’re not experienced with automotive repairs, it’s recommended to seek professional assistance.
• How much does it cost to repair a P1390 code?
  The cost can range from $500 to $1,000 depending on whether you need a timing belt replacement or sensor repairs.
• What should I do if my check engine light turns on?
  You should use an OBD-II scanner to check for codes like P1390 and address any issues accordingly.
• Can I reset my check engine light after fixing P1390?
  Yes, after completing repairs, you should reset your OBD-II system before taking your vehicle for a test drive.