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▷▷ 2021 ▷ How to read and understand Check Engine Light (OBD-II) codes

4 julio, 2021

Turning on the Check Engine Light is often a topic that car owners try to avoid talking about too much. It can be quite intimidating to see the little light on your vehicle’s dash light up suddenly, but in reality, it’s not something that should immediately paralyze you. By preparing yourself with a little automotive knowledge, a helpful tool, and general information on what this light is really trying to tell you, you will not only gain more peace of mind, but also develop a closer relationship with your vehicle.

Diagnostic Trouble Codes (DTCs) are automotive computer codes stored by the on-board computer diagnostic (OBD) system in your vehicle. There are literally hundreds of different codes that the Check Engine Light can represent. While that sounds daunting, with a little patience, tackling the basic diagnostics will give you useful knowledge about your vehicle and also allow the Check Engine Light to do what it’s really supposed to do – be your guide.

There are two acronyms to keep in mind when trying to find out more about Check Engine Lights. These two acronyms are OBD and DTC.

  • Tip: OBD codes refer to almost the same as DTC codes, which is why you will often hear them being exchanged in the auto industry. OBD codes are most often referred to as OBD-II, which has been the type of code since 1996.

OBD acronym table

Unfortunately, obvious and helpful vehicle symptoms don’t always accompany an illuminated Check Engine Light. Since there are hundreds of possible OBD codes, there are also hundreds of possible reasons for the light, including:

  • Computer output circuit problems
  • Emission control problems
  • Problems in the air and fuel metering systems
  • Ignition system faults
  • Speed ​​control and idle issues
  • Transmission problems

That is why it is important that someone who does not have a lot of automotive knowledge does not assume what a code means. When the Check Engine Light comes on, you should have it checked quickly by a certified mechanic. If your check engine light comes on because of a serious concern, you risk further damaging your car by not fixing the problem right away.

  • Warning: If the Check Engine Light comes on and blinks, it indicates a very serious concern. Find a safe place to stop, turn off your car, and have it diagnosed and repaired before continuing to use it.

Insert and read an OBD scanner

The Check Engine light comes on when a fault is detected in one of your vehicle’s monitored systems. To find out why the light is on, you need to read the codes through the OBD port.

You will need an OBD scan tool. The scanner allows you to communicate with the computer and retrieve fault codes. Some scanners can provide information on what the revealed code means, but most will only give a combination of five digits and letters.

Follow these 4 steps to insert and read the OBD scanner:

OBD port on the bottom of the glove compartment

Step 1: locate your vehicle’s OBD port. The most common mounting location for an OBD port is under the dash on the driver’s side near the pedals.

Legally it has to be within 3 feet of the steering wheel and it should not require tools to access it.

The connector is a 16-pin female connector that is trapezoidal in shape.

plug male to female connector

Step 2: plug your OBD scan tool into the connector. The male end of the scan tool will only fit one way into the vehicle’s connector.

The scan tool will turn on as soon as it has been connected.

obd scanner shown

Step 3: read the codes on the computer. Each scan tool will have different instructions on how to operate it, so read yours carefully.

Navigate to a heading called “Read Codes” and select it.

scanner showing code

Step 4: record the codes displayed. If there are multiple codes, they may change or you may have to press a button to see the next code.

  • Tip: It is very important to write these codes in the same order as they are displayed on the scanner. However, OBD codes will always appear on your scanner when it is connected to the OBD port or Data Link Connector (DLC).

Interpretation of OBD codes

OBD codes may seem complex, but underneath the letters and numbers, you can identify the general cause of your lit Check Engine Light, allowing you to take the next necessary steps.

box explaining how to read codes

Step 1: divide your code into sections.

1. The first section is the first character, which is always a letter.

two. The second section is the next character, which is a …

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