2003 Mitsubishi Lancer Has A Check Engine Light

Troubleshooting the Check Engine Light in Your 2003 Mitsubishi Lancer: Common Causes and Solutions

Find Repair Location
Reviewed by
Bo Fader
Written by RepairPal Car Genius
Updated January 14, 2025
0%
40% chance it's the
Emissions System
0%
60% chance it's
Something else
The most common reasons a 2003 Mitsubishi Lancer has a check engine light are an emissions system component, a sensor, or a catalytic converter.
  • Emissions System: A faulty emissions system component, such as an oxygen sensor or EGR valve, can lead to increased emissions and trigger the check engine light.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 2003 Mitsubishi Lancer has a check engine light?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

A faulty oxygen sensor is one of the most common causes of a check engine light. Symptoms may include a decrease in fuel mileage, hesitation or misfiring from the engine, rough idling or even stalling. A faulty sensor may cause the vehicle to fail an emissions test.

Due to the nature of electrical systems on modern vehicles, the range of problems these can cause are nearly limitless. However, there is a way to categorize them in two ways. Permanent and intermittent problems. Permanent problems appear and remain. This may be the vehicle will not start, the radio does not work, or the door chime will not turn off among many, many others. These problems are more straight-forward to diagnose since they present themselves at all time. This means there will always be a fault to find. Intermittent electrical problems, however, can be difficult or impossible to locate, since they appear then disappear without warning. The best case scenario for an intermittent issue is when replicating the problem is easily accomplished and understood. This allows a technician to make an issue semi-permanent, allowing them to find the fault. Other issues that come and go without warning and cannot be replicated on demand must occur when the technician is servicing the vehicle, otherwise there is no problem to correct. It is most important to understand that electrical system faults always require inspection, and can include the vehicle working in any manner, or not working at all.

Like we noted in the last section, general diagnosis symptoms are the most vague of the bunch. There are several diagnostic spectrums, electrical diagnosis, drivability diagnostics, engine diagnostics, transmission diagnostics, and the list could continue for about 5 or 10 more spectrums of diagnostics. The most important take-away here, is that general diagnostics are diagnostics that have no other spectrum in which they fit, or the problem is unknown. This means that any vehicle left outside of a repair facility with the keys and an authorization to perform diagnosis will be diagnosed under the general diagnosis spectrum.

When the Check Engine Light comes on, you may experience engine performance issues such as poor acceleration, rough idling, or an engine that won't start. In some cases, no abnormal symptoms will be experienced. Other systems like the transmission or ABS can cause the Check Engine Light to illuminate and lights for those systems can come on at the same time. Similar lights may say "Check Engine Soon", "Malfunction Indicator Light" or just "Check". In rare case the engine can overheat.

What are the initial diagnostic steps to take for a check engine light on a 2003 Mitsubishi Lancer?

When faced with a check engine light on your 2003 Mitsubishi Lancer, it's essential to adopt a systematic diagnostic approach to identify the underlying issue. Start by checking the gas cap; a loose or damaged cap is a common culprit that can easily trigger the light. Next, take a moment to scan the dashboard for any additional warning lights, as these can provide further clues about the problem. If no obvious issues are apparent, inspect the oxygen sensor, which plays a critical role in monitoring exhaust emissions and can cause the light to illuminate if faulty. Utilizing an OBD-II scanner is a crucial next step; it allows you to retrieve error codes from the vehicle's computer, offering specific insights into what might be wrong. Additionally, ensure that all essential fluid levels—such as oil, coolant, and transmission fluid—are adequate, as low levels can also lead to warning lights. Finally, don’t overlook the condition of your spark plugs; worn or damaged plugs can trigger the check engine light as well. By following these steps in order, you can effectively narrow down the potential causes of the check engine light and take appropriate action to resolve the issue.

What are the common problems that could cause the check engine light to illuminate in a 2003 Mitsubishi Lancer?

When the check engine light illuminates in a 2003 Mitsubishi Lancer, it signals the need for immediate attention to various potential issues affecting the vehicle's performance. One of the most frequent causes is a loose gas cap, which can disrupt the fuel system's pressure and trigger the warning light. Another common issue is a faulty oxygen sensor, which can lead to poor fuel economy and increased emissions. Problems with the catalytic converter, such as clogs or failures, are also significant contributors to the check engine light activation due to their critical role in emission control. Additionally, malfunctioning spark plugs or ignition coils can severely impact engine performance, while a defective mass airflow sensor can disrupt the air-fuel mixture, leading to further complications. Engine misfires, often resulting from fuel or ignition system issues, can also cause the light to illuminate. Other potential problems include a faulty EGR valve, vacuum leaks, malfunctioning thermostats, and even transmission-related issues. By understanding these common problems, DIY enthusiasts can effectively diagnose and address the underlying issues, ensuring their Mitsubishi Lancer operates smoothly and efficiently.

How urgent is it to address the check engine light on a 2003 Mitsubishi Lancer?

When the check engine light illuminates on your 2003 Mitsubishi Lancer, it is crucial to recognize the urgency of the situation. This warning light is not merely a nuisance; it indicates that there is a malfunction within the engine or emissions system that requires immediate attention. Ignoring this signal can lead to escalating problems, including severe engine damage, decreased fuel efficiency, and compromised vehicle performance. Moreover, continued neglect may pose safety risks while driving, as underlying issues could affect the vehicle's handling and reliability. For those inclined to take a DIY approach, it is advisable to first connect an OBD-II scanner to diagnose the specific trouble codes associated with the check engine light. This initial step can provide valuable insights into the nature of the problem, allowing you to make informed decisions about necessary repairs. However, if the issue appears complex or beyond your expertise, seeking professional assistance is essential to ensure that your vehicle remains safe and operational. Addressing the check engine light promptly not only protects your investment but also contributes to the overall longevity and performance of your Mitsubishi Lancer.

You’ve got options with RepairPal

Whether you need a more accurate auto repair estimate or help finding a reputable shop in your area, we’ve got you covered.