What is the check engine light on a 2013 Lexus GS 350?
The check engine light on a 2013 Lexus GS 350 is the car's Malfunction Indicator Lamp (MIL): a warning generated by the onboard diagnostics system that something in the engine, emissions, or drivetrain is not functioning correctly. It can turn on for anything from a loose gas cap to a serious engine fault.
What the light means for the GS 350
In the 2013 GS 350, the MIL is triggered by the ECM/ECU when sensors or emissions components report out-of-spec readings. The light can stay steady or flash, and the cause can range from trivial to critical. A steady light generally signals a fault that should be diagnosed, while a flashing light indicates a potentially severe misfire that can damage the catalytic converter if driven without service.
Common causes you might see recorded in the GS 350's memory include:
- Loose or faulty gas cap that fails EVAP tests
- Faulty oxygen (O2) sensors or mass airflow (MAF) sensor
- Bad spark plugs or ignition coils causing misfires
- Vacuum leaks or issues in the evaporative (EVAP) system
- Catalytic converter efficiency problems or damage
- Fuel delivery problems, such as clogged injectors
- Electrical wiring or connector faults in engine sensors
Note that this is not an exhaustive list. The MIL may be triggered by dozens of issues, and only a diagnostic code readout will pinpoint the exact fault.
How to diagnose and respond
If you see the MIL, start with simple checks and then read the diagnostic codes with an OBD-II scanner. Here are steps to take before making a repair appointment:
- Tighten the gas cap until it clicks, then drive 1–2 days to see if the light resets.
- Scan for codes using an OBD-II scanner or have a shop pull the codes. Record any stored codes and freeze-frame data.
- Observe any symptoms such as rough idle, reduced power, poor fuel economy, or unusual noises.
- Inspect obvious issues like vacuum hoses, damaged wiring, or signs of EVAP issues.
- If the light remains on after addressing a cap issue, or if it’s flashing, schedule diagnostics promptly.
The best course is to have a technician retrieve the OEM diagnostic codes and perform tests to verify the exact faulty component and to avoid unnecessary replacements.
What to expect at a service center
At a Lexus dealer or qualified shop, technicians will typically scan the vehicle with the OEM diagnostic tool, retrieve the exact stored codes, perform targeted tests (sensor performance, fuel delivery, EVAP checks, ignition checks), and replace the faulty component as needed. Costs vary depending on the issue, with simple fixes costing far less than major repairs like catalytic converter work. Always obtain a written estimate before authorizing work.
Costs to expect
Diagnostic fees commonly range from about $50 to $150. Fixes vary widely:
- Gas cap replacement or EVAP minor repairs: typically $50–$300 total
- Oxygen sensor or MAF sensor replacement: ~$200–$350 plus labor
- Spark plugs or ignition coils: ~$150–$450 plus labor
- Catalytic converter replacement: often $800–$2,500 or more, plus labor
Prices depend on location, labor rates, and whether OEM or aftermarket parts are used.
Summary
In short, the check engine light on a 2013 Lexus GS 350 signals that the onboard computer detected a fault in the engine, emissions, or related systems. Start with simple checks like tightening the gas cap, then pull the codes and seek a professional diagnostic to identify the exact cause and pursue the appropriate repair. Addressing issues promptly helps protect the vehicle’s performance, fuel efficiency, and long-term reliability.
What are common problems with the 2013 GS 350?
The most common recall is: Fuel Pump Inside Fuel Tank Fails Causing Engine Stall While Driving.
What is the most common reason for check engine light?
The most common reasons for a check engine light are a loose or faulty gas cap, a failing oxygen sensor, or bad spark plugs. Other frequent causes include a malfunctioning catalytic converter, a dirty mass airflow sensor, or vacuum leaks.
Common causes
This video explains the top reasons for the check engine light: 47sThe Auto BrainYouTube · May 5, 2025
- Loose or damaged gas cap: A loose or cracked gas cap can allow fuel vapors to escape, triggering the light. This is often one of the easiest fixes.
- Failing oxygen sensor: The oxygen sensor measures the amount of oxygen in your exhaust. If it's failing, it can lead to a drop in fuel efficiency and turn on the light.
- Bad spark plugs or ignition coils: Worn-out spark plugs or a failing ignition coil can cause engine misfires, leading to poor performance and triggering the light.
- Faulty catalytic converter: This component converts harmful exhaust gases into less harmful ones. A failing catalytic converter can cause a significant drop in fuel efficiency and performance.
- Dirty or faulty mass airflow sensor (MAF): The MAF sensor measures the amount of air entering the engine. Contamination or a malfunction can cause the light to come on.
- Vacuum leaks: Cracks or leaks in vacuum hoses can disrupt the air-fuel mixture and trigger the light.
What to do
- First, check that your gas cap is on tightly and is not damaged.
- If the light remains on, you can use an OBD-II scanner to read the specific code from your car's computer to diagnose the problem more accurately.
- Some issues, like a loose gas cap or minor vacuum leaks, can be fixed yourself. Others, like a failing catalytic converter or oxygen sensor, may require a professional mechanic.
What causes a Lexus check engine light?
The check engine light is part of your Lexus car's onboard diagnostics system. When the light comes on, it means the computer has identified a problem in the engine or another system, like the emissions system. Issues can range from a loose gas cap to serious engine problems.
Can I drive a Lexus with the check engine light on?
If your check engine light is flashing in your Lexus, we extraordinarily recommend not to drive the vehicle and schedule Lexus service today. Below is a list of the most accepted reasons your check engine light can come on: Your O2 Sensor (Oxygen Sensor) needs to be replaced.
