Check Engine Light Reappeared: What You Should Do

When the check engine light (CEL) comes on, it can be a cause for concern. However, sometimes it can be nothing more than a problematic code that appeared due to minor electrical or electronic deviations in the vehicle. This article will guide you through the situation you've described, what to do, and how to ensure that the issue is properly addressed.

Common Scenario

Your experience with a garage is a common one. You mentioned that you took your car to a garage, they reset some codes, and told you no further work was needed. However, within a week, the check engine light reappeared. Here’s a more detailed look at what likely happened and what steps you should take.

Scenario: You visited a garage named “Johnny's Quick Lube” for an oil change and to diagnose the CEL. They found a code for “small evap leak” and presumed it was a gas cap issue. Without further diagnosis, they sold you a new gas cap, overcharged you, and cleared the code.

Understanding the Issue

Codes can often be thrown for minor deviations in the vehicle's electrical or electronic system, even if there is no significant issue. If the code reappears, it suggests that further investigation is necessary. The garage may have cleared the code, but the underlying issue remains unresolved.

Codes are a symptom of a problem, not the problem itself. Let's assume the oxygen sensor is giving a false reading. Reseting the codes won't solve the issue; the oxygen sensor will need to be replaced, and then the codes can be cleared.

What Should You Do?

Step 1: Retain the Codes
Ask the mechanic to read the codes and take a picture of the information. If the repair shop provided the codes on the repair receipt, compare them.

Step 2: Contact the Shop
Call the shop and inform them of the reoccurrence of the check engine light. Request that they provide a warranty and fix the problem without further charges.

Step 3: Escalate if Necessary
Inform the shop that you expect a thorough diagnosis and repair, not just the replacement of parts. If they claim the issue is fixed, ask to see the failed components.

Step 4: Consider Independent Diagnostics
If the shop seems reluctant or uncooperative, consider taking your car to an independent mechanic for a second opinion. Some issues may require a diagnostic setup that the shop may not have.

Common Missteps by Mechanics

Unfortunately, many garages only perform the bare minimum to fix the problem and don't conduct a full diagnostic test. Often, they will perform a test drive, clear the codes, and tell you the light is off, but they might not address the underlying issue.

Codes can be reset after 2–3 drive cycles after the initial detection of the issue. Many shops do not perform a thorough diagnostic setup because either they lack the equipment or their personnel are not skilled in using it. If the codes are reappearing, it's an indication that a full diagnosis is necessary to identify and resolve the problem.

Conclusion

When faced with the reoccurrence of a check engine light, it's important to take a proactive approach. Retain the codes, contact the repair shop, and ask for a proper diagnosis and repair. If the issue is not resolved, consider seeking an independent diagnosis. Remember, the check engine light being on until the problem is fixed means that no matter how many times the codes are reset, the light will still come back on.

Additional Resources

For further guidance, you may want to look into:

How to Read a Check Engine Light How to Fix Your Check Engine Light Check Engine Light Problem Solver