2020 Subaru WRX Check Engine Light: Is It the Tune?

How to Fix check-engine-light

Dealing with a check engine light in your 2020 Subaru WRX can be frustrating. It often pops up at the most inconvenient times, leaving you wondering what's wrong and how urgently you need to address it. As one owner shared, even with a modified vehicle, unexpected issues can arise, stating, "This is your sign to put on winter tires I owe my neighbour a new fence and my car an apology." (source). Understanding the common triggers and how to address them can save you time, money, and stress. This guide will walk you through the process, based on real owner experiences and common issues.

Symptoms

When the check engine light illuminates in your vehicle, the symptoms can vary widely. Some owners may not notice any immediate changes in performance, while others might experience drivability issues. Some of the symptoms mentioned include issues related to control and traction, especially when driving in certain conditions.

A common symptom reported can be described as a lack of control. The car might feel unstable or difficult to handle, especially in challenging driving conditions. This can be exacerbated by factors like tire condition and road surface.

Traction issues are another frequent symptom. Owners might notice the vehicle slipping or struggling to maintain grip, particularly in wet or snowy conditions. This can manifest as wheel spin during acceleration or a general feeling of instability while cornering. As one owner noted, "Ive lived in the Midwest my whole life where it snows big just about every year throughout the winter. Ive got some year or so old general gmax A/S and it drove great!" (source). This highlights the importance of appropriate tires for the season.

Most Likely Cause

Based on owner discussions, a likely cause for check engine lights in the vehicle is related to the tune of the engine. The engine's tune refers to the calibration of its electronic control unit (ECU), which manages various aspects of engine performance, including fuel delivery, ignition timing, and boost pressure. When the tune is not properly optimized or is incompatible with other modifications, it can trigger a check engine light.

Modifying the factory tune of your 2020 Subaru WRX, especially to increase power or performance, can sometimes lead to unforeseen issues. A tune that is too aggressive or that doesn't properly account for specific aftermarket parts can cause the engine to run outside of its optimal parameters. This can result in problems such as excessive fuel consumption, misfires, or even damage to engine components.

How to Diagnose

Diagnosing a check engine light related to the engine's tune involves several steps. Here's a breakdown of the process:

1. Read the Diagnostic Trouble Code (DTC): The first step is to retrieve the DTC that triggered the check engine light. This requires an OBD-II scanner, which plugs into the diagnostic port of your 2020 Subaru WRX, typically located under the dashboard. Once connected, the scanner will display the DTC, which is a code that corresponds to a specific fault in the system.
2. Research the DTC: Once you have the DTC, research its meaning. Many online resources and repair manuals provide detailed explanations of DTCs and their possible causes. Understanding the specific fault that the code indicates will help you narrow down the potential issues.
3. Inspect the Tune: If the DTC points to a problem with the engine's tune, the next step is to inspect the tune itself. If you have access to the tuning software, you can review the settings and parameters to see if anything appears out of place. Compare the current tune to a known good tune or consult with a tuner to get their opinion.
4. Check for Modifications: Make a list of all aftermarket modifications that might be affecting the tune. This includes things like aftermarket intakes, exhausts, intercoolers, and fuel injectors. Ensure that the tune is properly calibrated to account for these modifications. If any of the modifications are not compatible with the tune, they may need to be adjusted or removed.
5. Data Logging: If you're still unsure about the cause of the check engine light, data logging can provide valuable insights. Data logging involves recording various engine parameters while driving, such as air-fuel ratio, boost pressure, and ignition timing. Analyzing this data can help you identify any abnormalities or deviations from expected values.
6. Consult a Professional Tuner: If you're not comfortable diagnosing the issue yourself, it's best to consult a professional tuner. A skilled tuner can analyze your data logs, inspect your tune, and identify any underlying problems. They can also make recommendations for adjustments or repairs.

Step-by-Step Fix

Fixing a check engine light related to a tune requires a systematic approach. Here's a step-by-step guide:

1. Identify the Problem: Use an OBD-II scanner to retrieve the DTC and research its meaning. This will give you a starting point for troubleshooting the issue.
2. Review the Tune: If the DTC points to a problem with the engine's tune, review the current settings and parameters. Compare it to a known good tune or consult with a tuner to get their opinion.
3. Check Modifications: Ensure that all aftermarket modifications are properly accounted for in the tune. If any modifications are not compatible, they may need to be adjusted or removed.
4. Adjust the Tune: If you're comfortable making changes to the tune, you can try adjusting the settings to address the issue. However, it's important to proceed with caution and only make small, incremental changes.
5. Data Logging: Data logging can provide valuable insights into the engine's performance. Record various engine parameters while driving and analyze the data to identify any abnormalities.
6. Reflash the ECU: If you have access to a known good tune, you can try reflashing the ECU with that tune. This will overwrite the existing tune and replace it with the known good one.
7. Seek Professional Help: If you're not comfortable making changes to the tune yourself, it's best to seek professional help from a tuner. They can diagnose the issue and make the necessary adjustments to the tune.
8. Reset the ECU: After making any changes to the tune, reset the ECU to clear the DTC and allow the system to relearn the new settings.
9. Test Drive: After resetting the ECU, take the vehicle for a test drive to see if the check engine light comes back on. Monitor the engine's performance and listen for any unusual noises or vibrations.
10. Monitor and Adjust: Continue to monitor the engine's performance and make adjustments to the tune as needed. It may take some time to dial in the perfect tune for your specific vehicle and modifications.

Parts and Tools Needed

• OBD-II Scanner: Used to read and clear DTCs.
• Laptop with Tuning Software: Required to access and modify the engine's tune.
• Data Logging Software: Used to record and analyze engine parameters.
• Tuning Cable: Connects the laptop to the vehicle's ECU.

Real Owner Costs

The cost of fixing a check engine light related to a tune can vary widely depending on the specific issue and whether you choose to DIY or seek professional help.

• DIY: If you have the necessary tools and knowledge, you can potentially fix the issue yourself for a relatively low cost. The main expenses would be the cost of an OBD-II scanner (around $50-$200) and any tuning software or cables required to access and modify the engine's tune.
• Professional Tuner: If you choose to seek professional help from a tuner, the cost can range from $100 to $500 or more, depending on the complexity of the issue. A tuner will typically charge an hourly rate for their services, which can vary depending on their experience and location.

Prevention

Preventing tune-related check engine lights involves several key steps:

1. Choose a Reputable Tuner: When modifying the engine's tune, choose a reputable tuner who has experience with the vehicle and the specific modifications you've made.
2. Use High-Quality Parts: Use high-quality aftermarket parts that are known to be compatible with the vehicle. Avoid using cheap or unreliable parts, as they can often cause problems.
3. Monitor Engine Performance: Regularly monitor the engine's performance and watch for any signs of problems, such as unusual noises, vibrations, or changes in fuel economy.
4. Perform Regular Maintenance: Perform regular maintenance on the vehicle, including oil changes, filter replacements, and spark plug replacements. This will help keep the engine running smoothly and prevent potential issues. As one owner shares, "Well when some sackless mouth breather with bald tires is going 40 mph on the highway in the left lane It makes me want to weld on a push bar and pit them into next year" (source).
5. Avoid Aggressive Driving: Avoid aggressive driving habits, such as excessive acceleration and hard braking. This can put unnecessary stress on the engine and increase the risk of problems.

What Owners Say

Real experiences from SUBARU owners:

Owner Experiences

"I feel bad for those who don’t get to experience ripping it up in the snow Lowered about an inch, ain’t nothing stopping me." — SUBUWUH (source)

"Lowered about an inch, ain’t nothing stopping me. Headphone or speakers for a beautiful redline" — SUBUWUH (source)

"Seen everyone talking about blizzards this and winter tires that. Ive lived in the Midwest my whole life where it snows big just about every year throughout the winter." — DueMolasses9571 (source)

FAQ

Q: How long does it take to fix a check engine light related to the tune?

A: The time it takes to fix a check engine light related to the tune can vary widely depending on the specific issue and whether you choose to DIY or seek professional help. If you're able to diagnose and fix the issue yourself, it may only take a few hours. However, if you need to seek professional help from a tuner, it could take several days or even weeks to resolve the issue.

Q: Can I drive with a check engine light on?

A: It's generally not recommended to drive with a check engine light on, as it could indicate a serious problem that could damage the engine. However, if the light is not flashing and the vehicle is running normally, you may be able to drive it for a short distance to get it to a repair shop.

Q: Is this a common issue on the vehicle?

A: Check engine lights can be a common issue on the vehicle, especially when the engine's tune has been modified. Aftermarket modifications can often cause unforeseen issues that trigger the check engine light.

Q: DIY vs mechanic - what's recommended?

A: Whether to DIY or seek professional help depends on your level of knowledge and experience. If you're comfortable working on cars and have the necessary tools, you may be able to diagnose and fix the issue yourself. However, if you're not comfortable working on cars or if the issue is complex, it's best to seek professional help from a mechanic or tuner. It's always recommended to have a professional diagnose the issue before attempting any repairs yourself. As another owner stated, "Alright so sticker bomb the door jams of my 02 with vape, cannabis and gooner stickers for shits n giggles." (source). While this isn't directly related, it highlights the importance of personal comfort levels when modifying your car.