The main emissions system problem I faced in my 2018 Honda Accord was a malfunctioning oxygen sensor that triggered the “emissions system problem” warning light. By replacing the faulty sensor, I was able to resolve the issue.
I’ve learned how complex yet vital the emissions control system is in today’s cars. My journey to diagnose and fix the emissions problem in my Accord taught me a lot about how the system works and what can go wrong with its many components.
In this article, I’ll share my expertise and insights to help other Honda owners troubleshoot and resolve emissions system issues in their 2018 Accord.
🧐 What Causes Emissions System Problems In The 2018 Honda Accord?
Table of Content
Based on extensive research and my first-hand experience, here are the most common culprits behind emissions system problems in the 2018 Accord:
🌡️ Malfunctioning Oxygen Sensor
The oxygen sensor measures oxygen levels in the exhaust to help the engine computer optimize combustion. If it fails, incomplete combustion can occur, releasing excess emissions. I diagnosed a faulty upstream oxygen sensor in my Accord using an OBD-II scanner after seeing the emissions system warning light.
🛢️ Fuel System Problems
Issues like a loose gas cap, leaking fuel injector, or failing fuel pump or pressure sensor can cause evaporative emissions system leaks. Fuel vapor leaks allow hydrocarbon emissions to escape into the air instead of getting burned in the engine.
😷 Clogged Air Filter
A restricted air filter reduces airflow into the engine, disrupting the optimal air-fuel ratio. This leads to incomplete fuel combustion and increased tailpipe emissions.
🔥 Catalytic Converter Failure
The catalytic converter plays a crucial role in treating toxic engine exhaust emissions. If it becomes clogged or damaged, exhaust gases bypass the converter, causing excess emissions.
🤔 Other Causes
Vacuum leaks, problems with the EGR valve, and faulty sensors like the MAF or cam/crankshaft position sensors can also cause emissions issues. Electrical problems like damaged connectors or wiring harnesses are another possibility.
🧰 How Do You Diagnose Emissions Problems In The 2018 Accord?
Diagnosing emissions system issues can be tricky without the right knowledge and tools. Here are some tips:
🚦 Check Engine Light
Emissions problems often trigger the check engine light (CEL). Use an OBD2 scanner to pull diagnostic trouble codes (DTCs) pointing to the source.
📉 Scan Tool Data
Compare sensor measurements from the scanner to factory specs. This helped me identify my oxygen sensor failure once I saw the voltage reading was out of range.
🧪 Visual Inspection
Look for obvious signs like leaks, damage, or missing emissions components. I always start diagnoses under the hood before diving into complex troubleshooting.
⏱️ Failure Symptoms
Take note if any other issues like poor acceleration, increased fuel consumption, rough idle, or hard starting occur alongside emissions problems. This helps narrow down causes.
👂 Listen
Unusual exhaust sounds or high-pitched whistling can indicate leaks needing repair. I listen closely on test drives to help pinpoint vacuum leaks or exhaust issues.
🔬 Smoke Test
A smoke machine can be used to detect tiny evacuation system leaks, allowing emissions to escape. Some pro mechanics use them for diagnoses.
🛠️ How Can The Emissions Problem Be Fixed In A 2018 Accord?
Repairing emissions issues varies case by case, but here are some common fixes:
▶️ Replace Faulty Sensor
Swapping out a failed component like an oxygen sensor, camshaft position sensor, or mass airflow sensor often resolves troublesome symptoms. Just take care to install an OEM Honda replacement part for reliability.
🔧 Tighten Fuel Cap
Simply properly tightening or replacing a loose fuel cap prevents evaporative leaks allowing emissions to escape from the fuel system.
🧽 Replace Air Filter
A restricted air filter reduces engine airflow, causing incomplete combustion. Swapping in a new filter restores performance.
⚙️ Mechanic Repairs
More complex issues like catalytic converter failure require mechanic diagnosis and repair. Proper troubleshooting to uncover the root cause is key before just replacing expensive parts.
🧑🔧 Can You Drive With The Emissions Light On In A 2018 Accord?
The short answer is technically yes, but I don’t recommend it outside of emergencies. Here’s why:
🚘 Reduced Performance
You may notice power loss, hesitation, or rough running driving with an active emissions trouble code. Performance is hampered to protect the emissions system.
😤 Increased Emissions
Driving with emissions problems allows higher levels of hydrocarbons, nitrogen oxides and other pollution to enter the air due to incomplete combustion and catalytic converter failure.
🔧 Risk of Costly Damage
Ignoring emissions problems can lead to oxygen sensor contamination, melted catalytic converters, and even engine failure over time as the air-fuel mixture drifts out of spec.
⚠️ Check Engine Light Stays On
The only way to turn off the check engine light, signaling an emissions problem, is to complete the proper repair. The light will stay illuminated if ignored.
🎟️ Potential Fines
Driving with a serious emissions system problem can earn fines in most inspection programs. Safety and air quality violations are issued to polluting vehicles.
Based on my education in automotive technology and experience servicing all types of cars over 20 years, I don’t recommend casually driving around with emissions problems in your Honda Accord.
Complete the required repairs to protect your engine, resolve performance issues, avoid fines, and reduce environmental impact from excess vehicle emissions before hitting the road!
🔧 How Much Does It Cost To Fix Emissions System Problems In A 2018 Honda Accord?
Unfortunately emissions related car repairs have a wide cost range – some simple, others complex. Here’s a breakdown:
Repair | Average Cost |
Loose Gas Cap Replacement | $20-50 |
Oxygen Sensor Replacement | $120-250 |
Mass Airflow Sensor Replacement | $140-320 |
EGR Valve Replacement | $370-650 |
Fuel Injector Replacement | $450-850 per injector |
Catalytic Converter Replacement | $1,000-1,800 |
EVAP System Smoke Test + Repair | $150-350 |
Labor varies per repair |
As you can see, a basic oxygen sensor swap may fix an issue for a couple of hundred bucks, while a catalytic converter job runs over a grand. Without proper diagnosis, parts cannon repairs waste money and might not solve root causes.
I always recommend scanning for trouble codes, verifying fixes with live data, and inspecting connections to pinpoint problems accurately before replacing components. This prevents paying big labor costs for misguided repairs!
Frequently Asked Questions
What Triggers The Emissions System Warning In A 2018 Accord?
The check engine light and “emissions problem” warning most often appear when the engine computer detects higher than normal hydrocarbon (HC) emissions in the exhaust stream. This signifies combustion issues.
Why Does My Accord Lose Power When The Emissions Light Turns On?
The engine computer activates “limp mode” to protect the emissions system when detecting problems. By limiting power output, excess stress is reduced to prevent costly damage as you drive with emissions issues.
What Are The First Steps I Should Take When My Accord’s Emissions Warning Appears?
Don’t panic! First, safely pull over and check that the gas cap is fully sealed. Then, use a scanner tool to pull the Diagnostic Trouble Codes (DTCs) pointing to the emissions problem at hand. Specific repairs vary by code.
Can I Pass My State’s Emissions Test If My Check Engine Light Is On For Emissions Problems?
Unfortunately, not all 1996 and newer cars require repairing serious emissions problems and passing an OBD test without stored codes to pass annual inspections. Some leniency exists for evaporative leaks.
How Urgent Is It To Fix An Emissions Problem Code – Can This Damage My Accord’s Engine?
It’s smart to address emissions issues right away to prevent stall conditions, reduce catalyst overheating risk, and avoid melting pistons or valves over time as the engine runs out of tune. A detailed diagnosis is recommended.
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