Back to Blog Academy

The Best OBD Scanner for Emission System Issues

By Joe Ballard
Published on May 16th, 2024

As an Amazon associate, we earn from qualifying purchases.

The emission system in late-model vehicles is a complex network of components, all working together to measure, filter, and remove harmful gases from the exhaust. If you've failed an emission test or your vehicle is running poorly, it's likely a problem with one of these components. While the issue may seem obvious, it could be more complex, underscoring the need for specialized knowledge and tools.

The Best OBD Scanner for Emission System Issues.jpg__PID:4d98ad2d-9f5e-4c0d-a152-406956d41995

In most cases, a sophisticated tool such as an OBD scanner will be required to pinpoint the problem component. However, by learning how to use this tool effectively, you can take control of your vehicle's health.

This article will guide you through the process, describing some common warning signs and explaining how you can use an OBD scanner to identify and repair the component causing the problem. This knowledge will empower you to take charge of your vehicle's maintenance.

What are the Warning Signs of an Emission System Problem

It may sound simple, but a loose gas cap can cause your vehicle to fail an emission test. Fumes will escape if the cap doesn't seal tightly, harming the environment. Checking your engine's air filter and cleaning or replacing it are practical steps you can take. If these don't resolve the issue, it's time to dig deeper, empowering you to take control of the situation:

  • The check engine light (CEL) is on – The CEL is a crucial indicator that can come on for many reasons, but if you also notice one of the other symptoms listed below, then there is a good chance that one of the emission system components is at fault. Understanding the role of the CEL in identifying emission system issues is key to effective troubleshooting. By understanding these signs, you can feel more informed and knowledgeable about your vehicle's health and be better equipped to address any issues that arise.
The Best OBD Scanner for Emission System Issues 2.jpg__PID:1fa00f28-dae5-49fb-ad89-bdf653854660
  • You notice a raw fuel smell—This could be a sign of a failing evaporative emission control canister, especially if you smell raw gas near the rear of the vehicle.
  • Reduced engine performance – These problems include abrupt stalling, rough idling, or misfiring.
  • Emission test failure – This is pretty obviously an emission component failure.
  • Unusual odors—These include a sulfur smell or possibly a burnt oil smell, which indicates a leak somewhere in the emission system.

If you notice any of these warning signs, it is recommended that you get out your Innova 5610 scanner and run through the comprehensive emission tests. If you have not yet invested in an OBD scanner, you should bring your vehicle to a professional mechanic for diagnosis and repair. Please keep in mind that the warning signs will provide clues that there is a problem, but to identify and fix the problem, you need to pinpoint it, which requires a diagnostic tool.

The Best OBD Scanner for Emission System Issues 3.jpg__PID:f7057f35-4edc-43cc-bf12-9238acfeeb3b

Find the perfect scanner in 1 minute

Key Takeaways

Observing unusual issues associated with your vehicle will pay off in the long run. In most cases, you will see a CEL come on, which is the first indication of a problem, but others can also signal an emission system problem. Signs such as decreased fuel economy, rough idling, misfires, sluggish performance, unusual engine noises or smells, stalling, and black smoke or soot from the exhaust pipe are all possible things to watch for.

The Best OBD Scanner for Emission System Issues 4.jpg__PID:7f354edc-03cc-4f12-9238-acfeeb3bdb88

The best course of action to identify the specific problem is to utilize an OBD scanner. Using my 2019 Hyundai Ioniq as an example, I connected the Innova 5610 scanner and the RepairSolutions2 app to perform the O2 Sensor test, an OBD Monitor test, and an EVAP Test. These tests are used to reliably pinpoint specific emission system problems so that you can fix them. By combining the OBD scanner with the Innova RepairSolutions2 app, you will identify the problem and receive information on estimated costs to replace the component.

Several subsystems comprise the Emission System, and a failure of any of the components in these subsystems will display a warning sign and eventually trigger a CEL. Let’s take a look at these systems in a bit more detail:

  • The Exhaust Gas Recirculation (EGR) system collects unburned fuel vapors that are combined with new fuel entering the combustion chamber. The typical replacement costs for an EGR valve range from $250 to $350.
  • The Positive Crankcase Ventilation (PCV) valve is located on the intake manifold. It collects leaked combustion gases, combines them with ventilating air, and reburns them in the combustion chamber. Depending on the vehicle type, the typical replacement cost for a PCV valve ranges from $50 to $100.
  • The catalytic converter consists of an insulated chamber containing ceramic pellets or a ceramic honeycomb-like structure coated with a thin metal layer, such as Palladium or Platinum. It converts the exhaust gases that pass through the converter to water vapor. The typical replacement costs for a catalytic converter range from $900 to $3500.
  • The Evaporative (EVAP) control system consists of a canister of activated charcoal capable of holding up to 35 percent of its own weight in fuel vapors. The EVAP system is a closed system designed to collect unburned fuel vapors and send them to the combustion chamber, where they are burned. The typical replacement costs for an EVAP cannister depend on the vehicle but can range from $400 to $1000.
  • The Oxygen (O2) sensor measures the oxygen levels in the exhaust that leaves your engine. Several O2 sensors are located near the exhaust manifold and several further down the exhaust pipe. When an O2 sensor is damaged, you may notice engine misfires or poor fuel economy. The typical replacement costs for an O2 sensor range from $150 to $500.


It is important to remember that being proactive in addressing emission system problems ensures that you maintain your vehicle's performance and reduce the environmental impact of pollution coming from your vehicle. Taking quick action if you notice any of the warning signs by using an OBD scanner or seeking professional help will enable you to diagnose and fix problems before they end up leaving you stranded with a large repair bill.

Back to Blog Academy

Have Questions?

Hop in the discussion board on our community site!
It's a place where we help each other answer questions. Like Reddit but for automotive lovers.

Visit Community