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How to Check Engine Light Codes without a Scanner

BY: Adam Karner
Mechanic is using a diagnostic car code reader for a check engine light

An unexpected check engine light can create a momentary feeling of panic, especially if you’re in the middle of traffic with somewhere to be. Don’t worry, though. In most cases, a check engine light is the first sign of something being wrong in your car and doesn’t necessarily mean catastrophic engine failure. The check engine light is connected to your vehicle’s power train, including the engine, transmission, or emissions system. A check engine light could be as minor as a loose gas cap or a faulty fuel pump. However, don’t immediately rule out the potential for expensive engine repairs, even if your vehicle runs smoothly.

Since the 1980s, nearly every vehicle produced has come equipped with an onboard diagnostics (OBD) system that allows the car to self-assess, self-diagnose, and report findings by storing specialized codes, known as diagnostics trouble codes (DTC) for owners and technicians. By scanning these check engine light codes using an automotive diagnostic scanner, you’ll be better able to narrow down the severity and cause of your check engine light.

What Does My Check Engine Light Mean?

How can you tell what a check engine light means without a scanner? If you’re stuck in traffic or don’t have time to investigate, an easy way to identify if you need to pull over immediately or if you can put off a trip to the repair shop until your next day off is by observing the color of your warning light on the dashboard. How your check engine or service engine soon light appears is a good indicator of the issue severity, for example:

Solid Yellow or Orange: If your check engine light is a solid yellow or orange, your onboard diagnostic system (OBD) has detected that a component or a system isn’t functioning correctly. The vehicle isn’t able to compensate for the problem and needs attention. When your check engine light is solid yellow or orange, the problem isn’t emergent, and you can likely wait until your next day off to investigate. However, you should only drive up to 100 miles before at least scanning the system with an OBD-II scanner to narrow down the cause of the problem.

Solid Red: When your check engine light is a solid red and is not blinking or flashing, it can mean that the problem needs attention sooner rather than later but isn’t catastrophic. If your check engine light is red, it is recommended that you drive to your nearest ASE Certified mechanic, repair shop, or car dealership for diagnostics and repair.

Flashing Check Engine Light: If your check engine light blinks, it could indicate a severe problem, potentially a misfiring engine. The best course of action is to pull over immediately and contact roadside assistance or towing to bring the vehicle to an ASE Certified mechanic, repair shop, or car dealership.

The Easiest Way to Read OBD2 Car Codes

The onboard diagnostics system allows drivers and technicians to assess vehicle health and safety quickly and effectively through an OBD-2 scanner. Scan tools are available at most auto parts stores, and some locations will perform a complimentary scan. Once accessed, the OBD-2 (or OBD-II) scanner can give information about the check engine light and the vehicle identification number (VIN), calibration identification number, and other crucial vehicle information.

In most passenger vehicles, an OBD2 port is easily located and accessed on the driver’s side of the car on the underside of the dashboard. Finding out the OBD2 codes and the source of your check engine light is as easy as plugging in the scanner and following these easy steps:

  • Step 1: Plug the OBD2 scanner into your vehicle’s OBD2 port
  • Step 2: Turn on the vehicle
  • Step 3: Enter any necessary information requested by the OBD2 scanner, such as the VIN
  • Step 4: Press “scan” on the code reader to initiate the scan
  • Step 5: After a few seconds, the OBD2 scanner will provide easy-to-follow prompts to deliver trouble or error codes for you to write down and record.

Simple Trick to Turn Off Check Engine Light

If you have access to an OBD scanner, a simple trick is to turn off your check engine light once the repair is done. Following the steps above, you can add another step to clear codes. Scroll to find the option to erase the fault code and press “enter.”

Please note that while this should reset your check engine light, keep in mind that if the repair isn’t done, the check engine light will inevitably return to remind you of the problem.

How to Read Car Engine Codes without a Reader

If you do not have access to an automotive diagnostic scanner, there are alternative ways to read codes without a scanner. Although these are not ideal, using your odometer or ignition key can effectively retrieve diagnostic trouble codes to determine the cause of your check engine light.

Method 1: Use Your Odometer Reset to Check Engine Light Codes

If you need access to diagnostic codes, look further than your vehicle’s odometer. You can read your engine’s diagnostic trouble codes using your odometer and following these easy steps:

  • Step 1: Press and hold the odometer’s reset button
  • Step 2: While holding the odometer’s reset button, press and hold the odometer’s trip button
  • Step 3: While holding down both the odometer’s trip and reset buttons, turn the ignition switch to “on”
  • Step 4: After turning the ignition on, release the odometer’s reset and trip buttons
  • Step 5: The diagnostic trouble code should appear in your odometer display for you to record

Method 2: Use Your Odometer Reset with Multiple Ignition Cycles

If method one didn’t work, your vehicle might require multiple ignition cycles to display the fault code rather than one. The steps will be similar to method 1, except, instead of simply turning the vehicle ignition to the on position, you’ll turn it “on,” then “off,” then “on” again, using these steps:

  • Step 1: Press and hold both the odometer’s reset and trip buttons
  • Step 2: While holding down the odometer’s trip and reset buttons, turn the ignition switch to “on”
  • Step 3: Hold the odometer’s trip and reset buttons while turning the ignition switch back to the “off” position
  • Step 4: Without letting go of the odometer’s trip and reset buttons, turn the ignition switch back to the “on” position again
  • Step 5: While the vehicle remains in the “on” position, release the odometer’s trip and reset buttons to display the trouble code in your odometer’s window

Method 3: Use the Ignition Key and Check the Dashboard

The ignition key is one of the more commonly used ways of diagnosing check engine light trouble codes without an OBD-2 scanner. However, while this method is easy, it takes careful observation to determine the DTC. If your vehicle is OBD-2 capable, the trouble code should appear within the odometer display, as in the methods above.

However, if your vehicle is older or uses an OBD-1 system, your engine scanner code will appear as a series of pulses and pauses in your engine light. Therefore, you’ll need to observe and count the number of pulses and pauses carefully. Each pulse denotes a digit, and a break separates the digits. So, for example, pulse, pulse, pulse, pulse, pulse, PAUSE, pulse, pulse, pulse can be interpreted as 53 (five pulses, a pause, and three pulses = 5 and a 3 = 53).

Once you understand what you’re looking for, you can find the code using these easy steps:

  • Step 1: Turn the key in the ignition “on” and “off” three to five times without turning the engine on, and end with the ignition in the “on” position
  • Step 2: If all the warning lights on your dashboard illuminate, you’ve turned the ignition enough times
  • Step 3: Watch for all lights to turn off except the check engine light
  • Step 4: Check if the diagnostic trouble code appeared in the odometer’s display
  • Step 5: If the odometer’s display is not showing a DTC, carefully watch the engine light and record the pulses and pauses to determine your trouble code

Method 4: Use a Paperclip to Access Your Diagnostic Trouble Codes

If any of the methods above were unsuccessful, your vehicle might not support the OBD-2 diagnostic system. However, there are ways to access the OBD-1 codes using only a paperclip or a jumper wire and following these steps:

  • Step 1: Ensure your car is turned to the off position
  • Step 2: Locate two terminals on your vehicle’s OBD port underneath your vehicle’s steering wheel
  • Step 3: With the car still in the “off” position, create a closed circuit to your onboard diagnostic system by connecting the two ports using the paperclip or jumper wire
  • Step 4: Turn the ignition switch to the “on” position without turning the engine over (cranking the vehicle)
  • Step 5: Record the pattern of pulses and pauses on your engine light to obtain your check engine trouble code, as described in method 3

Method 5: Take Your Vehicle to a Professional

Although there are ways to check engine light codes without a code scanner, the easiest and most effective way is to use an OBD-2 scanner. If one is unavailable, auto part stores sometimes offer a complimentary scan to help you identify the cause of your check engine light.

However, even if you have the engine scanner codes, the trouble codes are sometimes generic and cannot be used for a complete and accurate diagnosis. Taking your vehicle to an ASE Certified mechanic, repair shop, or car dealership is an effective way to identify the cause of the check engine light code and have it repaired to get you back on the road.

Endurance Warranty Can Protect You From Expensive Engine Repairs

While many drivers may be tempted to ignore the check engine light or procrastinate on taking a trip to the shop, especially if the vehicle seems to be driving smoothly, in reality, it could indicate a severe problem that should be addressed immediately. Operating your vehicle with even minor problems could lead to more serious issues, like a blown catalytic converter, irreversible damage to oxygen sensors (O2 sensors), or other expensive engine repairs. Ignoring a problem can result in potentially thousands of dollars worth of expensive engine repairs. An extended warranty or auto protection plan can help protect you from unexpected costly engine repairs.

Endurance Warranty offers customizable auto protection plans with flexible payment options, giving you peace of mind that your vehicle (and your wallet) are protected against unexpected mechanical breakdowns. In addition, Endurance offers a wide variety of auto protection plans to cover more budgets, driving styles, and vehicles, even if your factory warranty has expired or you’ve been denied extended warranty options with other providers. Explore auto protection plans for older vehicles, high mileage vehicles, cars with salvage or rebuilt titles, luxury vehicles, commercial use vehicles, Canadian Grey market cars, hybrids, diesel, and more.

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Whether you drive a Chrysler, Dodge, or Honda, don’t wait until your check engine light pops up. Start protecting your vehicle today by requesting a free, no-obligation quote for an auto protection plan. You can also speak directly with a member of the award-winning Endurance customer care team by calling (800) 253-8203 today. Explore more topics on our blog, including learning what to do if your check engine light comes on, what your dashboard warning lights are telling you, whether or not brakes could cause your check engine light to come on, and more.

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