How to Read Engine Light Fault Codes Without a Scan Tool
When the check engine light comes on, it often means there’s an underlying issue that needs attention. However, not everyone has access to a specialized scan tool to diagnose the problem.
There are methods available for reading engine light fault codes without a scanner. Regardless of if you have an OBD1 or OBD2 system, you can follow three simple steps to access fault codes without a scanner.
Join us as we discuss reasons for the check engine light to be on and guide you through the steps to retrieve fault codes directly from your dashboard. Become better equipped to understand what’s happening under the hood and take appropriate action, whether that means a simple fix or seeking professional repair.
Why is My Check Engine Light On?
The check engine light (CEL) is an integral part of the onboard diagnostics system in your vehicle. This makes it the most commonly recognized indicator of performance issues, especially for those without a scan tool on-hand. Here’s a rundown of some of the most common reasons why your check engine light is on:
Loose or Damaged Gas Cap: The gas cap maintains fuel pressure and prevents evaporative emissions. If it’s not sealed properly, it might trigger your engine light to come on.
Faulty Oxygen Sensor: A faulty oxygen sensor will cause increased fuel consumption and harmful emissions.
Bad Catalytic Converter: If the catalytic converter is not working properly, your vehicle will experience rough engine performance and reduced efficiency.
Malfunctioning Mass Airflow Sensor (MAF): If the MAF fails, it’ll lead to poor engine performance, increased emissions, and reduced fuel economy.
Spark Plugs or Wires Issues: Faulty or worn-out spark plugs and ignition wires can cause misfires, which results in poor engine performance. This will usually cause the check engine light to come on. Components like these require regular maintenance and replacement.
Fuel Injector Problems: Clogged or malfunctioning fuel injectors can prevent the engine from receiving the right amount of fuel.
Exhaust Gas Recirculation (EGR) Valve Issues: When the EGR valve clogs up or malfunctions, it usually results in an increase in emissions.
Battery or Charging Problems: Issues with the vehicle's battery or charging system can affect electronic components and cause the check engine light to come on. Ensure the battery connections are secure and the battery is in healthy condition.
Transmission Issues: Some transmission-related problems can trigger the check engine light. These include issues with the transmission control module (TCM) or low transmission fluid levels.
As you can see, the issues that can cause your check engine light to turn on vary widely. Reading the specific fault code is the only way you can know for sure what might be causing the issue. Luckily, you can usually get the check engine light fault code to show without a scanner.
A Quicker Way to Read Engine Light Fault Codes Without a Scanner (for OBD2 Drivers)
If your car has an OBD2 system, there’s a quicker way to retrieve fault codes from your odometer display without a scanner. Follow these quick steps:
Hold the trip button and odometer reset button simultaneously.
While doing so, turn the ignition on and then immediately let go of the trip button and odometer reset button.
Read the fault codes that appear on your odometer display. Write down the codes and refer to your vehicle’s repair manual for information about the codes and their meanings.
How to Read Engine Light Fault Codes Without a Scan Tool
To read engine light fault codes without a scanner, all you should need is your car’s ignition key. Follow these three simple steps.
Step 1: Without fully starting your engine, turn the ignition key on and off at least 3 times. The goal is to end with the ignition in the “on” position without getting the engine running. You’ll know you’ve done this correctly when all the dashboard warning lights turn on. If the lights don’t turn on after three tries, restart and try turning it on and off 4-5 times.
Step 2: Next, look at the dashboard. All the lights should turn off except the “service engine” light. The engine code will appear on the odometer display (if you have a newer car with an OBD2 system). If the engine code doesn’t appear on the odometer display, the check engine light will instead flash corresponding to a specific fault code. Quick flashes mean “1”, while long blinks mean “10”. Add the numbers together to find your fault code. If your engine light stays lit up and is not flashing, then it’s likely a problem with the ECU.
Example: Let’s say my Honda’s engine light flashes quickly three times, and then does two long blinks. Quick flashes equal 1, while long blinks equal 10. This means my error code is 23 (1+1+1+10+10). On a Honda, fault code 23 indicates an issue in the knock sensor.
Step 3: Take down the codes and refer to your vehicle’s repair manual for more information on each fault code and what the issue is.
Autel: The Best Way to Read and Troubleshoot Passenger Vehicle Fault Codes
When it comes to fault codes that are not related to your engine light, accessing those is near impossible without a scan tool.
An advanced scan tool can read fault codes across your vehicle, including in complex components like DEF (Diesel Exhaust Fluid) systems, transmission control modules, ABS, and more.
Issues in these components require immediate attention, and could lead to costly repairs down the road if not resolved. That’s why Autel is a must-have for professionals and even hobbyists who prefer to save money with the D.I.Y route.
Equip yourself with Autel, our chosen diagnostic tool when it comes to the essentials. Autel’s products match expert features and capabilities with unparalleled affordability. By purchasing an Autel scanner from WholeFleet Diagnostics, you get access to expert advice and troubleshooting support from our experienced team!
