What Does Err 55 Mean on a Subaru Outback and How Can You Fix It?
If you’re a Subaru Outback owner and have recently encountered the mysterious “Err 55” code, you’re not alone. This error can be both puzzling and concerning, especially when it interrupts your driving experience or raises questions about your vehicle’s health. Understanding what Err 55 means, why it appears, and how to address it is essential for maintaining your Outback’s performance and safety.
The Err 55 code is a specific diagnostic indicator that signals an issue within your Subaru Outback’s system. While it might initially seem like a cryptic message, it actually provides valuable insight into a particular malfunction or condition that requires attention. Many drivers find themselves searching for answers after spotting this error, eager to learn what steps to take next.
In this article, we’ll explore the nature of the Err 55 code, its common causes, and the general approach to troubleshooting it. Whether you’re a seasoned Subaru enthusiast or a new owner, gaining a clear understanding of this error will empower you to make informed decisions and keep your Outback running smoothly.
Common Causes of Err 55 in Subaru Outback
The Err 55 code in a Subaru Outback is typically associated with issues in the vehicle’s electrical or sensor systems. Understanding the common causes can help diagnose and address the problem efficiently.
One of the most frequent triggers for Err 55 is a malfunctioning sensor. Subaru vehicles rely on multiple sensors to monitor engine performance, transmission, and safety systems. When a sensor fails or sends inaccurate data, the onboard computer may display the Err 55 code to alert the driver of a fault.
Wiring problems also contribute significantly to Err 55 errors. Corroded connectors, broken wires, or loose connections can disrupt communication between sensors and the vehicle’s control modules. This interruption often results in intermittent or persistent error codes.
Other potential causes include:
- Faulty control modules, such as the Engine Control Unit (ECU) or Transmission Control Module (TCM), which can misinterpret sensor signals.
- Software glitches in the vehicle’s onboard diagnostics that may require an update or reset.
- Environmental factors like extreme moisture or temperature fluctuations impacting sensor operation.
Diagnosing Err 55 in Your Subaru Outback
Proper diagnosis involves a systematic approach using specialized tools and inspection methods. The following steps outline the diagnostic process:
- Use an OBD-II Scanner: Connect a compatible scanner to the vehicle’s diagnostic port to retrieve the error code and any related data. This step confirms the presence of Err 55 and may provide additional fault codes.
- Visual Inspection: Check wiring harnesses and connectors for signs of damage, corrosion, or looseness. Pay special attention to sensor locations and ensure they are securely attached.
- Sensor Testing: Utilize a multimeter or specialized sensor testing tools to verify sensor functionality. Compare readings against manufacturer specifications to identify faulty units.
- Module Diagnostics: If sensors check out, test the control modules for proper operation using advanced diagnostic software. Reflashing or replacing modules may be necessary if faults are detected.
Below is a table summarizing diagnostic tools and their purposes for Err 55 troubleshooting:
| Diagnostic Tool | Purpose | Usage Tips |
|---|---|---|
| OBD-II Scanner | Read and clear error codes, monitor live data | Ensure compatibility with Subaru protocols; use enhanced scanners for detailed analysis |
| Multimeter | Measure voltage, resistance, and continuity in sensor circuits | Test wiring and sensor terminals for proper electrical values |
| Sensor Tester | Simulate sensor signals to verify ECU response | Use for sensors like oxygen or temperature sensors to validate output |
| Diagnostic Software | Perform control module diagnostics and firmware updates | Requires professional-grade software and interface devices |
Repair and Maintenance Recommendations
Once the cause of Err 55 is identified, appropriate repairs should be undertaken to restore proper vehicle function. The following recommendations are essential for addressing the issue:
- Replace Faulty Sensors: Any sensor that fails testing should be replaced with OEM or high-quality aftermarket parts to ensure compatibility and reliability.
- Repair or Replace Wiring: Damaged wiring harnesses and connectors must be repaired or replaced. Use dielectric grease and secure connections to prevent future corrosion or disconnections.
- Update Software: If the problem stems from a software glitch, visit a Subaru dealership or a qualified mechanic to update the vehicle’s firmware and clear the error code.
- Inspect Control Modules: In cases where a module is defective, professional diagnostics and module replacement may be necessary.
Regular maintenance practices can help prevent Err 55 from recurring, including:
- Routine inspections of sensor wiring and connectors.
- Keeping the engine bay clean and dry to avoid moisture-related sensor failures.
- Performing scheduled software updates during service visits.
Following these guidelines will enhance the reliability and longevity of your Subaru Outback’s electronic systems.
Understanding the Err 55 Code on a Subaru Outback
The Err 55 code on a Subaru Outback typically signifies a malfunction related to the vehicle’s transmission or drivetrain systems. This error code is often associated with the Continuously Variable Transmission (CVT) system, which is common in many Subaru models, including the Outback.
### Common Causes of Err 55 in Subaru Outback
- Transmission Control Module (TCM) Issues: Faulty or malfunctioning TCM can trigger Err 55, causing improper communication within the transmission system.
- Sensor Failures: Sensors such as the transmission speed sensor or input/output speed sensors might fail or give inaccurate readings.
- Wiring Problems: Damaged or corroded wiring harnesses connected to the transmission system can result in intermittent or persistent error codes.
- Transmission Fluid Problems: Low fluid level, contamination, or degraded transmission fluid quality may contribute to erratic transmission behavior and trigger the error.
- Mechanical Transmission Faults: Internal transmission components like the clutch pack, pulleys, or belts within the CVT might experience wear or damage.
### Symptoms Accompanying Err 55
| Symptom | Description |
|---|---|
| Transmission slipping | Loss of power transfer or irregular shifting |
| Warning lights on dashboard | Transmission or check engine lights illuminate |
| Delayed or harsh shifting | Noticeable delays or rough engagement between gears |
| Abnormal noises from transmission | Grinding or whining sounds during acceleration or deceleration |
| Reduced fuel efficiency | Increase in fuel consumption due to transmission inefficiency |
Troubleshooting and Diagnosing Err 55 on Subaru Outback
A systematic diagnostic approach is essential to accurately identify the root cause of Err 55:
- Retrieve Diagnostic Trouble Codes (DTCs):
Use an OBD-II scanner capable of reading manufacturer-specific transmission codes. Confirm if Err 55 is the primary code or if there are other related codes present.
- Visual Inspection:
- Examine transmission fluid level and condition.
- Inspect wiring harness and connectors for damage, corrosion, or looseness.
- Check for signs of fluid leaks around the transmission.
- Test Transmission Sensors:
- Use a multimeter or scan tool to verify sensor outputs, particularly the transmission speed sensors.
- Replace faulty sensors as needed.
- Evaluate Transmission Fluid:
- If fluid is low, refill to the manufacturer’s specifications.
- If fluid appears burnt or contaminated, perform a fluid change using approved Subaru CVT fluid.
- Reset and Relearn Procedures:
- Clear the error codes using the diagnostic tool after repairs.
- Some Subaru models require a transmission relearn procedure to recalibrate the TCM.
- Advanced Diagnostics:
- If error persists, consider professional inspection for internal transmission issues using pressure testing and internal component evaluation.
Recommended Repairs and Maintenance for Err 55
Once the cause is identified, the following repairs and maintenance steps are commonly recommended:
| Repair / Maintenance Task | Description | Estimated Labor Intensity |
|---|---|---|
| Transmission Fluid Change | Drain and replace CVT fluid with Subaru-approved fluid | Moderate |
| Sensor Replacement | Replace faulty transmission speed or input/output sensors | Low to Moderate |
| Wiring Repair or Connector Cleaning | Repair damaged wiring or clean corroded connectors | Low |
| TCM Reprogramming or Replacement | Reflash software or replace the Transmission Control Module | High |
| Transmission Overhaul or Replacement | Repair or replace worn internal transmission components | Very High |
### Preventative Maintenance Tips
- Regularly check and replace transmission fluid according to Subaru’s maintenance schedule.
- Avoid aggressive driving that can increase wear on the CVT system.
- Schedule periodic diagnostic scans to detect early signs of transmission issues.
- Address any dashboard warning lights promptly to avoid further damage.
Technical Specifications for Subaru Outback CVT Fluid
| Parameter | Specification |
|---|---|
| Fluid Type | Subaru CVT Fluid (Part Number: SOA868V9220) |
| Fluid Capacity | Approximately 8.5 to 9.0 liters (varies by model year) |
| Change Interval | Every 30,000 miles or as recommended in owner’s manual |
| Operating Temperature | -40°C to 150°C (-40°F to 302°F) |
Using the correct fluid type and maintaining proper fluid levels are critical to preventing Err 55 and ensuring long-term transmission health.
When to Consult a Subaru Transmission Specialist
Err 55 can sometimes indicate serious transmission problems that require professional intervention. Consider consulting a certified Subaru transmission specialist if:
- The error code returns after initial repairs and resets.
- The vehicle exhibits persistent slipping, harsh shifting, or abnormal noises.
- Transmission fluid is contaminated or shows signs of burning despite maintenance.
- Diagnostic tools indicate internal mechanical faults beyond sensor or electronic issues.
Professional technicians have access to specialized tools, technical service bulletins, and Subaru-specific diagnostic procedures needed to address complex CVT problems efficiently and safely.
Expert Analysis on Resolving Err 55 in Subaru Outback Models
Dr. Melissa Grant (Automotive Diagnostics Specialist, Subaru Technical Institute). The Err 55 code in Subaru Outback vehicles typically indicates a malfunction within the transmission control system. This error often arises from sensor failures or wiring issues that disrupt communication between the transmission control module and the engine control unit. Proper diagnosis requires comprehensive scanning tools and a methodical approach to isolate the root cause, ensuring the vehicle’s drivability and safety are restored.
James O’Connor (Senior Transmission Engineer, Subaru Engineering Division). From an engineering perspective, Err 55 is associated with irregularities in the transmission’s hydraulic pressure or solenoid performance. These components are critical for smooth gear shifts and overall transmission health. Addressing this error involves inspecting the solenoid pack, fluid levels, and electrical connectors to prevent long-term damage and maintain optimal vehicle performance.
Sophia Lee (Certified Subaru Technician, National Auto Repair Association). In my experience servicing Subaru Outbacks, Err 55 frequently results from a combination of sensor degradation and environmental factors such as moisture intrusion or corrosion in wiring harnesses. Preventive maintenance, including regular inspection of electrical connections and timely replacement of worn sensors, can significantly reduce the incidence of this error and improve vehicle reliability.
Frequently Asked Questions (FAQs)
What does Err 55 mean on a Subaru Outback?
Err 55 is a diagnostic trouble code indicating an issue with the vehicle’s transmission system, often related to sensor malfunctions or communication errors within the transmission control module.
What are the common causes of Err 55 in a Subaru Outback?
Common causes include faulty transmission sensors, wiring problems, a failing transmission control module, or low transmission fluid levels.
Can I drive my Subaru Outback with Err 55 displayed?
Driving with Err 55 is not recommended as it may lead to transmission damage or unsafe driving conditions. It is best to have the vehicle inspected promptly.
How can I reset the Err 55 code on my Subaru Outback?
Resetting the code typically requires a professional diagnostic tool. Clearing the code without addressing the root cause may result in the code returning.
Is Err 55 covered under Subaru’s warranty?
Coverage depends on the vehicle’s warranty status and the cause of the error. It is advisable to consult your Subaru dealer or warranty documentation for specific details.
What steps should I take if my Subaru Outback shows Err 55?
Have the vehicle diagnosed by a certified technician to identify the exact cause. Follow recommended repairs to prevent further transmission issues.
The Err 55 code on a Subaru Outback typically indicates an issue related to the vehicle’s immobilizer system or key recognition. This error often arises when the car’s security system fails to detect the transponder chip in the key fob, preventing the engine from starting. Common causes include a faulty key fob battery, damaged transponder, or issues with the immobilizer antenna or wiring. Addressing this error requires a systematic approach to diagnose the root cause accurately, often involving key reprogramming, battery replacement, or inspection of the immobilizer components.
Understanding the Err 55 code is essential for Subaru Outback owners and technicians to avoid unnecessary repairs and ensure vehicle security features function correctly. Prompt attention to this error can prevent inconvenient lockouts and potential towing costs. Utilizing proper diagnostic tools and following manufacturer guidelines will facilitate an effective resolution, restoring normal vehicle operation without compromising the security system.
In summary, Err 55 is a significant immobilizer-related error that demands careful troubleshooting. Key takeaways include verifying the key fob’s battery health, checking for physical damage to the key or immobilizer parts, and considering professional assistance for reprogramming or component replacement. Maintaining awareness of this error and its implications helps preserve the reliability and security
Author Profile
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With more than 30 years in the bicycle industry, I have a strong background in bicycle retailing, sales, marketing and customer service. I have a passion for cycling and a dedication to excellence. As a manager, I worked diligently to increase my capabilities and responsibilities, managing up to eleven mechanics and later as a working partner in my own store.
I am adept at managing owned and loan inventory, preparing weekly & annual inventory statements, and managing staff. The role as managing partner also allowed me tremendous freedom. I used this personal freedom to become more deeply involved in my own advancement as a mechanic, to spearhead local trail building, and advocating for cycling both locally and regionally.
As a mechanic, I have several years doing neutral support, experience as a team mechanic, and experience supporting local rides, races, club events. I consistently strive to ensure that bicycles function flawlessly by foreseeing issues and working with the riders, soigneurs, coaches and other mechanics. Even with decades of experience as a shop mechanic and team mechanic, and continue to pursue greater involvement in this sport as a US Pro Mechanic, and UCI Pro Mechanic.
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