What does the check emission system Acura light mean? We have gathered factual information about check emission system alerts. Read on and fix your car emission problem. So, what does emission system problem mean? The emission control system in Acura cars limits the discharge of harmful gases from the internal combustion engine. The vehicle uses this mechanism that involves a series of functions to keep emissions very low. Once you see the check emission light on car, the Engine Control Unit (ECU) is alerting you of an issue with the vehicle’s emissions. Several reasons cause the check emission system warnings to show up in cars. But we will discuss one primary system that carries all Acura emissions system problem: The Fuel Evaporative Emission Control System (EVAP).

What is the Fuel Evaporative System?

When you hear of vehicle emissions, your thoughts go to the exhaust pipe. In fact, the exhaust pipe is the preferred point of emission. But the gasoline fumes can evaporate through the car engine, the fuel delivery system, and the tank. So if all these components face intense pressure from gasoline vapors, they can allow harmful fumes out. The Fuel Evaporative Emission Control System (EVAP) prevents toxic gasoline fumes from escaping to the atmosphere when the fuel rests in the tank or the delivery system components. Surprisingly, there are several EVAP systems depending on the car model. But in this article, we will look at the standard EVAP system. photo: Fuel Evaporative Emission Control System (EVAP)  

How Does a Modern EVAP System Work?

The major components of a Fuel Evaporative Emission Control System (EVAP) are: 
  • Fuel cap - it closes the end of the pipe that directs gasoline to the tank. The fuel cap has a vacuum relief valve that opens if the system has faults.
  • A fuel tank - a safe container that holds a specific volume of gasoline for the car.
  • Vapor canister - also known as the charcoal canister- stores gasoline vapor from the gas tank.
  • Fuel tank pressure sensor - it measures the pressure in the gasoline tank.
  • Hoses - they deliver fuel vapor to the canister and back when the fuel-air mixture turns back to normal.
  • A purge valve - also called a canister purge solenoid, is a valve that opens to allow fuel vapor from the canister to the engine.
  • Canister vent valve - closes off the canister when the system is under self-diagnostics.
A fuel Evaporative Emission Control System (EVAP) is a computerized system, and its operations can be broken down into three phases. Below are the three phases of the EVAP operation: Phase 1: Self-Diagnostic The system checks for leaks and the whole operation in general. This test sequence is called the EVAP monitor, where the monitoring strategy varies depending on the vehicle year and model. Check your Acura model user manual to see the description of how its EVAP monitor functions. Phase 2: Storing Gasoline Vapor Once you switch off the vehicle engine, all the fuel vapor is moved to the vapor canister. The canister is the main component of the EVAP system. It’s made of activated charcoal that traps vapors and prevents them from escaping to the atmosphere. However, the canister has a mechanism to open for fresh air to enter without releasing the gasoline vapor. It only completely closes when the EVAP monitor is activated. Phase 3: Purging Fuel Vapors The Engine Control Unit (ECU) controls the whole EVAP. So, when the engine is on, it monitors the conditions to determine whether more combustion is required. Finally, it sends the signal to the solenoid to open the purge valve. photo: EVAP Once the purge valve is open, a vacuum is created to allow more air into the canister. The air mixes with the fuel vapor, and the mixture moves to the engine combustion chamber.

What Are the Signs Of Fuel Emission System (EVAP) Failure?

Apart from the check Emission System light warning in Acura, three other signs can alert you of the EVAP failure. Read them below:

1. High Gas Mileage

If the Fuel Evaporative System isn’t working correctly, the fuel vapor will escape to the atmosphere once pressure builds up rather than being stored for later use. As such, you will learn of the high gas mileage, but in a real sense, the engine doesn’t burn all this fuel. Most of it is lost to the surrounding.

2. Gasoline Smell Around the Car

Once the system starts releasing fuel vapor to the surrounding, you will smell gas in the interior and the exterior of the car. First, this is very dangerous because it can cause fire around the vehicle. Second, you risk getting fined for polluting the environment.

3. Tighten Fuel Cap Warning Message

Once the pressure builds up in the fuel system, the fuel cap may open the vacuum relief valve. The cap bleeds all the vapor, and the fuel tank pressure sensor may sense a high vacuum. As such, the module may assume a leak in the system or the untightened fuel cap. photo: Tighten Fuel Cap Warning Message   In most Acura models, the check fuel cap light will illuminate any time the fuel Evaporative System malfunctions. So, it’s essential to diagnose all the EVAP issues if it doesn’t go off.

What are Annual Emissions Testing and EVAPs?

Annual emissions tests are done by inspecting the car to check if it properly functions and emits the recommended amount of gases into the atmosphere. The inspector normally measures the amount of pollutants the vehicle emits through the exhaust system. Also, the inspector checks the Fuel Evaporative Emission Control System (EVAP) condition to learn if the car releases unburnt gasoline fumes into the environment. However, you must do some repairs if the vehicle doesn’t meet the requirements. The testing costs and the fines after discovering emission faults vary depending on each state's rules.

How Do You Fix Engine Emission Warning in Acura TSX?

I would like to give one emission warning solution for various Acura models as outlined below:
  • Check emission system Acura TSX
  • Acura MDX check emission system flashing light.
  • Check emission system Acura RDX dashboard alert.
  • Check emission system Acura MDX yellow dashboard light.
Once the check emission system Acura light illuminates, park the car and tighten the gas cap. Usually, the module interprets the loose gas cap as a Fuel Evaporative System problem. However, if you tighten the cap and the vehicle check emission system warning light doesn’t go off, your EVAP system has a severe issue that needs a specialist. Ideally, drive to the nearest diagnostic shop or call a mechanic to visit you. The mechanic will analyze the case and decide how to fix emission system problem. The mechanic may sometimes fix the EVAP issue, but the light does not go off immediately. At this point, you need to reboot the car's computer system by disconnecting the battery. Simply carry out the following procedure. Step 1: Switch off the car engine and let it cool to avoid burning your hands. Step 2: Open the hood and locate the car battery around the engine. It’s generally fixed on one side of the engine. photo: the car battery around the engine1 Step 3: Locate the negative terminal and disconnect it. Typically there are two terminals labeled (-) and (+). You need the appropriate size spanner wrench to loosen the terminal. photo: the car battery around the engine2   Step 4: Wait for around 60 seconds and reconnect the terminal. The car’s check emission system light will go off immediately. But if it fails to go off, you need to consult a specialist.

Frequently Asked Questions (FAQs):


Can I Drive My Car If it Says Check Emission System?

If the check emission system light is on, you can drive the vehicle for a few miles to search for the nearest mechanic. However, you should be very keen to note the vehicle’s performance, gas mileage, and other factors that may lead to more damage. Completely ignoring the check emission system can cost you much on repairs.


How Do You Know When to Replace Your Gas Cap?

Most car manufacturers design gas caps to last 50,000 miles or more. And most gas caps are set to click when they close tight. So, if your car’s gas cap remains loose after tightening, you will need to replace it. Normally, if the cap is faulty, the emission control lamp illuminates to alert you. Also, if the cap goes missing, you definitely have to replace it.


What Happens If Fuel Cap is Loose on My Acura?

If you ignore your loose fuel cap, you risk losing most of the fuel as vapor. Secondly, dust and grime can find their way into the fuel tank and clog the fuel filter and pump. Third, you risk your car catching fire due to the gasoline vapor escaping to the surrounding. Also, your car’s check the emission system light will illuminate.


How Can I Improve My Emissions and Avoid Future Problems?

Have your car’s Fuel Evaporative System(EVAP) checked and repaired to avoid future emission problems. Then, do regular car service to ensure every car component works normally. And if your car gets old, sell it and buy a newer model.


How Do You Reset the Gas Cap Error?

Open the gas cap and retighten it until it clicks. However, not all car models are designed with a clicking gas cap. But if the cap tightens, the warning light will go off.

Final Thoughts

Check emission system Acura means the Fuel Evaporative Emission Control System(EVAP) is malfunctioning. The EVAP system consists of the fuel cap, fuel tank, fuel tank pressure sensor, purge valve, and canister vent valve. If the causes of EVAP faults warning are minor such as a loose gas cap or the computer system reboot, you can do it yourself. Else, if the causes are major, you should visit the diagnostic and repair shop.