Mitsubishi Expo Has A Check Engine Light

Common Causes of the Check Engine Light in Your Mitsubishi Expo and How to Resolve Them

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Reviewed by
Devin Cabugcal
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 Mitsubishi Expo 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 Mitsubishi Expo 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.

Any time there is an emissions fault the check engine light will be displayed. The purpose of the check engine light is to inform the driver that an emission related fault has been found, and that there are on-board diagnostic (OBD) trouble codes stored in the powertrain or engine control module. Additionally, since the emissions systems are so intertwined into engine control and transmission control systems, symptoms may include nearly any sort of drivability concerns. This may include harsh shifting, failure to shift, hesitation on acceleration, jerking, engine failure to start or run, loss of power, or any number of other drivability issues.

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.

Troubleshooting Check Engine Light in a Mitsubishi Expo

When faced with a check engine light in your Mitsubishi Expo, it's essential to adopt a systematic diagnostic approach. Start by checking the simplest potential issues, such as ensuring that the gas cap is securely tightened, as a loose cap can often trigger the light. Next, inspect the condition of your spark plugs and ignition coils, as worn components can lead to misfires and poor engine performance. If these basic checks do not resolve the issue, consider examining the mass airflow sensor and oxygen sensors, which are critical for maintaining optimal air-fuel ratios. A dirty or malfunctioning sensor can significantly impact engine efficiency and emissions. If the light persists after these checks, utilizing an OBD-II scanner can provide specific error codes that will guide you to more complex issues, such as problems within the transmission or engine timing systems. By following this methodical approach, you can effectively identify and address the underlying cause of the check engine light, ensuring your Mitsubishi Expo runs smoothly.

What Common Problems Cause the Check Engine Light to Illuminate in a Mitsubishi Expo?

When the check engine light comes on in your Mitsubishi Expo, it can be a source of concern, but understanding the common problems can empower you to take action. One frequent culprit is a faulty oxygen sensor, which is essential for monitoring exhaust air levels and optimizing fuel combustion. If the sensor is dirty or damaged, it may provide inaccurate readings, leading to the light's illumination. Similarly, a dirty mass airflow sensor can disrupt the air-fuel mixture, affecting engine performance. Worn spark plugs and bad ignition coils are also significant factors; they can cause misfires and hinder the combustion process, triggering the warning light. Additionally, a simple issue like a loose gas cap can lead to fuel vapor leaks, prompting the check engine light to activate. By addressing these common problems promptly, you can maintain your Mitsubishi Expo's performance and prevent further damage, making it easier to manage repairs on your own.

Why is the Check Engine Light On in a Mitsubishi Expo?

When the Check Engine Light illuminates in your Mitsubishi Expo, it serves as a crucial warning that should not be ignored. Neglecting this signal can lead to serious consequences, including decreased fuel efficiency, engine misfires, and even catastrophic engine damage. For instance, a faulty oxygen sensor can not only affect your vehicle's performance but also lead to increased emissions, which could result in costly repairs or fines. Additionally, issues like a malfunctioning ignition cylinder or a dirty mass airflow sensor can compromise your vehicle's safety and reliability. By addressing these symptoms early, you can prevent further complications and maintain your vehicle's efficiency. Regular maintenance checks and timely diagnostics are essential for DIY enthusiasts looking to keep their Mitsubishi Expo running smoothly. Taking action at the first sign of trouble not only saves you money in the long run but also ensures a safer driving experience.

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