GM OBD1 and OBD2 Codes Full List for Free Download

Do you drive a Chevy model ranging between 1982-1995? Are you curious about how to read, interpret the OBD1 codes for your GM car? 

Reading trouble codes in your GM vehicle could be easier than toasting your bread. In fact, if you’re reading the trouble codes without the help of a scanner, the only necessary requirement is an unrolled paper clip. 

Towards the end of the article, you will be capable of performing a self-diagnostic test with or without a scanner. You will learn to read the trouble codes, interpret them, and identify the faulty component or sensor. Additionally, you get to clear the trouble codes at the comfort of your garage with little sweat and with less or no penny spent. 

Keep reading to find out more!

GM OBD1 Codes Full List

Free Download: GM OBD1 Code List FULL (PDF)

GM Manufacturer-specific OBD2 Codes Full List

Free Download: GM Manufactured-Specific OBD2 Code List FULL (PDF)

NOTE: For some code numbers, there may be more than one definition because the same number may be used for different faults on different model years or models.

How to Read OBD1 Codes for GM with a Paper Clip

Do you ever get frustrated with why the check engine light keeps flashing on your vehicle, or do you just want to know the fault causing you much discomfort and disturbance while driving? Here are the steps to follow to diagnose the faulty system in your Chevy vehicle:

1. First, locate the diagnostic plug underneath the dashboard. It should include 10 female pins and has a black plastic casing. 
2. Unroll a paper clip and fold it into a U or V shape. 
3. Insert the ends of the unrolled paper clip through pins A and B, which are the two top right pins on the plug. These steps automatically shift the vehicle to diagnostic mode. 
4.  Next, start the ignition but be careful not to start the engine. 
5. Fix your eyes on the instrument cluster. Your primary focus should be the check engine light which should start blinking at any moment. 
6. The diagnostic systems communicate via iterative blinking of the check engine light. Counting the number of blinks should tell you the error code.
7. The vehicle groups error codes in 2 digits and each is iterated 3 times. 
8. The first time the vehicle will blink once, pause, then twice to symbolize code 12. This code means the start of the diagnosis. The code is repeated thrice before trouble codes begin displaying. 
9. The vehicle will iterate through the error codes, which you should record with a pen and paper, then finish with a code 12 indicating the end of the process.
10. Turn the ignition off and pull out the paper clip before looking up the meaning of the codes in Google. 

How to Read OBD1 Codes on GM with a Scanner

Why improvise when you could get a scanner to perform the same function as the paper clip. GM scanners help in reading the error codes without jeopardizing the system’s electronic circuitry. Here is how to use it:

1. Insert the scanner onto the diagnostic plug, which should be located beneath the dashboard. Ensure that it is inserted correctly for its pins to mesh with the plug’s pins A and B. 
2. Turn on the ignition but be careful not to rev up the engine. 
3. Check the check engine light. It should flash once then twice, indicating a code 12 that represents the start of diagnostic mode. Each code will be iterated thrice. 
4. Next, the check engine light will flash several times to indicate the trouble codes. You should note and record them with a piece of paper and pen. It would help if you got a partner to assist by writing down the codes or counting the number of flashes that you might miss if you did the work on your own.
5. After the system displays all the error codes, it will flash a code 12 indicating the end of the diagnosis. 
6. Switch off the ignition.
7. Look up the error code in Google for clarity of the faulty component. Or you could come back to this page after this procedure and look it down below in our GM OBD1 code list. 

READ MORE: Generic OBD2 Codes List for All Cars [Updated 2021]

How to Clear GM OBD1 Codes

GM OBD1 codes are super easy to remove. You don’t have to do anything at times, and starting your car three or four times will eliminate the trouble codes. Nevertheless, there is a quicker method that is also relatively easy to execute. Here is how to do it:

1. Locate the battery in your car, which should be located somewhere underneath the engine compartment. 
2. Using a wrench, loosen the bolt reinforcing the plug to the negative terminal. The negative terminal should have a minus symbol on it, and a black cable should be mounted using a plug on it. 
3. Disconnect the cable from the negative terminal.
4. Wait for 30 to 60 seconds before reconnecting the cable to the negative terminal. 
5. Tighten the bolt with the wrench.
6. Turn on the ignition and check if the error code is removed.
7. If the check engine light is still flashing, repeat the above procedure a second time, only that this time you wait for 1 to 2 minutes. 

READ MORE: Best GM Scan Tools 2021 [Review and Comparison]

Final Thought

Flashing engine light doesn’t have to frustrate or distract you while you can quickly identify the fault within your vehicle. Best of all, you won’t have to spend a dime with the DIY techniques mentioned in the post.

By looping with a paper clip through pin A and B for the diagnostic plug, you can count the number of flashes displayed by the check engine light to identify the trouble code. Or even better, you could get an excellent scanner, and you don’t have to worry about looping through the wrong terminal. Counting the number of flashes will reveal the trouble codes in your vehicle.