Lexus ES350 Has A Check Engine Light

Troubleshooting Common Causes for the Check Engine Light in Your Lexus ES350 and How to Resolve Them

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Reviewed by
Aisha
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 Lexus ES350 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 Lexus ES350 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 Lexus ES350

When faced with a check engine light in your Lexus ES350, it's important to adopt a systematic diagnostic approach. Begin by checking the simplest potential issue: the gas cap. A loose or damaged gas cap can trigger the light, and simply tightening it may resolve the problem. If the light persists, consider using an OBD2 scanner to retrieve the fault codes from your vehicle's computer. This tool will provide specific information about the underlying issue, allowing you to focus your efforts on the most likely culprits. If the check engine light is flashing, this indicates a more serious problem, and you should turn off the engine immediately to prevent further damage. As you progress through your diagnostics, remember that while some issues can be easily fixed at home, others may require professional expertise. Always prioritize safety and consider consulting a mechanic if you encounter complex problems that are beyond your skill level. By following this structured approach, you can effectively troubleshoot the check engine light and maintain the health of your Lexus ES350.

What Common Problems Cause the Check Engine Light to Illuminate in a Lexus ES350?

When the check engine light comes on in your Lexus ES350, it can be a source of frustration, but understanding the common problems can help you diagnose the issue effectively. One frequent culprit is a malfunctioning ignition cylinder, which can lead to irregular engine performance. Additionally, issues with the exhaust gas oxygen sensor may cause misfires, particularly noticeable during sudden acceleration or low-speed driving. A surprisingly simple fix could be a loose gas cap, which is often overlooked but can easily trigger the check engine light. Engine misfires, especially severe ones, can also result in unburned fuel entering the exhaust system, prompting the warning light. Furthermore, fault codes stored in the engine control module can activate both the check engine and VSC lights, indicating a need for further investigation. Lastly, vacuum leaks can lead to high or rough idle and poor fuel efficiency, making them another potential reason for the light's illumination. By being aware of these common issues, you can take the first steps toward diagnosing and potentially resolving the problem yourself.

Why is the Check Engine Light On in a Lexus ES350?

When the Check Engine Light illuminates in your Lexus ES350, it serves as a crucial warning that should not be ignored. This light can signify a range of issues, from minor problems like a loose gas cap to more serious concerns such as a malfunctioning catalytic converter or engine misfires. Ignoring these warnings can lead to significant engine damage, decreased fuel efficiency, and even safety hazards while driving. For instance, a flashing Check Engine Light indicates a severe engine misfire, which can cause damage to the catalytic converter if not addressed immediately. Therefore, it is essential to take these alerts seriously and seek professional diagnostics as soon as possible. By doing so, you not only protect your vehicle's performance but also ensure your safety on the road.

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Lexus ES350 Check Engine Light: Causes & Solutions