2018 Ram 3500 Has A Check Engine Light

Troubleshooting the Check Engine Light in Your 2018 Ram 3500: Common Causes and Solutions

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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 2018 Ram 3500 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 2018 Ram 3500 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.

What are the initial diagnostic steps to take for a check engine light on a 2018 Ram 3500?

When faced with a check engine light on your 2018 Ram 3500, it's essential to adopt a methodical diagnostic approach to identify the issue effectively. Start by checking the gas cap, as a loose or damaged cap is a common and easily fixable cause of the warning light. Next, monitor your dashboard gauges for any unusual readings that could signal a more significant problem. A visual inspection under the hood is also crucial; look for any signs of damage to wires, hoses, or connectors that could affect vehicle performance. If these initial checks do not resolve the issue, using an OBD-II scanner can provide valuable error codes that pinpoint the problem. Additionally, take note of any other symptoms your vehicle may exhibit, such as strange noises or rough idling, as these can help narrow down potential causes. Finally, consulting your owner's manual can offer specific insights into what the check engine light may indicate and guide your next steps. By following this structured approach, you can efficiently diagnose and address the issue, ensuring your Ram 3500 runs smoothly.

What are the common problems that could cause the check engine light to activate in a 2018 Ram 3500?

When the check engine light illuminates in a 2018 Ram 3500, it can signal a range of common issues that are often manageable for DIYers. One of the simplest problems to check is a loose gas cap, which can easily be tightened or replaced if damaged. Another frequent culprit is a faulty oxygen sensor; while replacing this part requires some mechanical knowledge, it can significantly improve fuel efficiency once addressed. Additionally, issues with the catalytic converter can arise, often indicated by unusual exhaust smells or decreased performance, and while this may require professional help, understanding the symptoms can guide your next steps. The mass airflow sensor is another component that can malfunction, affecting engine performance and fuel economy, and can be cleaned or replaced with the right tools. Spark plug or ignition coil issues are also common, leading to misfires that can be diagnosed through engine performance tests. Lastly, an engine misfire can stem from various factors, including bad spark plugs or fuel injectors, and recognizing the signs early can prevent further damage. By being aware of these potential problems, you can take proactive measures to diagnose and address the check engine light issue in your Ram 3500, ensuring your vehicle runs smoothly and efficiently.

How urgent is it to address the check engine light on a 2018 Ram 3500?

When the check engine light illuminates on your 2018 Ram 3500, it is essential to recognize the urgency of the situation. This warning light is not merely a nuisance; it signals potential issues within your vehicle's engine or emissions system that could escalate if left unaddressed. While some problems may be minor, others could lead to significant damage, resulting in costly repairs and compromising your vehicle's performance and safety. For DIY enthusiasts, the first step is to use an OBD-II scanner to retrieve diagnostic trouble codes, which can provide insight into the specific issue at hand. This proactive approach allows you to assess the severity of the problem and determine whether it can be resolved with simple repairs or if professional assistance is necessary. Ignoring the check engine light can lead to more severe complications, so taking prompt action not only safeguards your vehicle's health but also enhances your driving experience. Remember, addressing the check engine light early can save you time, money, and stress in the long run.

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