OBD Port Not Working? Try These Fixes

OBD Port Not Working

On-board diagnostic, which is abbreviated as OBD, is a car’s inbuilt troubleshooting system. It provides self-diagnosis for your car and gives repair possibilities to the mechanic. Your car has a computer that monitors sensors that measure exhaust gas mixture, engine temperature, and other metrics. The computer keeps track of the sensors to ensure that all the measurements are within the manufacturer’s optimum range. In cases where they are not within the optimum range, the computer takes note and stores it as an error code. Modern cars have multiple error codes, all pointing at different issues.

Mechanics access error codes to determine the general state of the engine. A scan is plugged into the computer port found on your vehicle, scanned, and then the codes are downloaded. All the error code’s translations are found on websites like OBD-codes.com. After getting the code’s translation, you can go on with your maintenance and repairs.

The OBD is the standard system used across all vehicles to retrieve diagnostic information for your vehicle. This information is produced by the engine control unit, ECU of your vehicle. OBD makes fleet solutions and telematics possible. It would be impossible to send the data collected by your car’s computer without the OBD. The collected data diagnose the car’s problems before they manifest. This makes you proactive and not reactive. The data also tracks tear and wear trends in different parts of the vehicle and why some components wear faster.

Determine if your OBD is functioning properly can be done in 3 easy steps;

Step 1 – Turn off your engine before you start.

Step 2 – Turn the key in the ignition on and run to crank the engine.

Step 3 – Be sure to look out for the check engine lights on the dashboard. The lights should go on briefly before they go off. This flash is an indication that the system is functioning well and is up to task monitoring the performance of your car.

Important: If you want to save $100s in servicing, diagnosis, and repair costs, improve your car's performance significantly and increase its value by 1.2x with little effort, download our Beginners Auto Maintenence & Repair Manual now. 
If the check engine light stays on after coming on, then that is an indication of a fault in the engine, emission system, or even the transmission. This should be checked and repairs made where applicable.

If the check engine light doesn’t come on completely, this is an indication that something is faulty with the system.

The OBD port is the area where you plug in any OBD tool to get your vehicle’s information. The OBD port is often the tracking devices’ primary part, as it is responsible for the ongoing power for the tracking devices. OBD port is usually located under the dashboard on the driver’s side, but this depends on the vehicle type.

Reasons Why Your OBD Port is not Working

If you scan your vehicle’s computer for OBD codes and get no readings, here are the possible causes;

Blown Fuse

Plugging into the OBD port and reading nothing could be due to a blown fuse. The engine control unit shares the same fuse circuit with other electrical components like the cigar lighter. On some vehicles, the lighter tends to blow up fuses. No fluid going to the engine’s control unit means no scan readings. The electronic control unit is the central part of the OBD system. The ECU collects data from a number of sensors within the vehicle. This data is then used to control the car’s components like the fuel injector or to monitor issues.

Here are the Symptoms of a Failing Engine Control Unit

Check Engine Lights Turn on

The engine check lights usually come on when a circuit and sensors problem is detected. However, there are instances when the engine check lights illuminate for no particular reason. Scan the vehicle’s computer for codes to diagnose the cause of the check engine lights on.

Engine Misfiring or Stalling

Unexpected engine behaviors could also mean that you have a failing engine control unit. A failing engine causes misfiring and stalling in your vehicle. This symptom may be irregular without any predictable pattern.

Poor Engine Performance

A faulty Engine control unit may disrupt the fuel settings and the regular timings in your engine, which will significantly affect the engine’s performance. Your car will reduce its power, fuel efficiency, and slow down acceleration.

Car not Starting

When starting the car or when the car does not start completely, problems can be attributed to a faulty engine control unit. If the engine control unit completely fails, your car’s engine management control will be ineffective; hence the car won’t start. Without the computer’s crucial inputs, your engine may just crank and not start, or it may not just start completely. Starting problems in vehicles are not exclusive to the faulty engine control unit. A complete diagnosis should be made to determine the cause of this symptom.

Poor Fuel Economy

A faulty engine control unit does not allow regulation of the amount of fuel that burns in the combustion chamber. Fuel will then not be economized in the combustion chamber, resulting in more fuel consumption than it should consume.

The computer inputs have to be accurate to give clear signals and keep things working smoothly. Fix your engine control unit (ECU) for a smooth driving experience.

Why You Have OBD Codes in the First Place

The main reason why you have codes to diagnose in the first place is because there’s a problem in your vehicle and this has sent a signal to the diagnostics unit and the problem has been stored as an error. The most common reason why people have problems with their cars is that they fail to maintain it. Maintenance is a compulsory thing that needs to be carried out by every car owner and if not done, certain components will fail and this will be expensive to repair at the dealership.

If you want to avoid problems or other issues and save $100s of dollars that you’ll spend at the dealership, you’ll need to service your vehicle often – you can use our mechanic-rated Auto Maintenance and Repair Manual to do this. It’s basically what mechanics use to go through your vehicle to check if there are any problems that need fixing. As soon as they notice the most minor problem, they’ll ask you to fork out some money even though it’s a problem you can fix yourself in a few minutes – the manual will teach you how to maintain your vehicle every few thousand miles and it’ll teach you how to fix minor problems that mechanics will ask you to pay for; saving you money in the long run.

A lot of our readers have this maintenance manual printed on their garage walls and a lot of them haven’t visited the mechanic in a few years because they know what to do to avoid problems. All it takes is giving your vehicle a little attention every few thousand miles and you’ll never spend money at the dealership again.

Causes of Engine Control Unit Failure

Corrosion and Moisture

Damage due to excessive moisture or corrosion is the most likely reason for engine control unit failure. Over time, the car gets exposed to harsh elements, and faulty seals will allow in moisture while corrosion comes from the wiring harness.

Faulty Fuel Solenoid

A corroded solenoid can cause a short in the engine control unit. The solenoid fails due to corrosion faster than the ECU. When your car runs just fine, then you turn off the engine, and it just won’t restart, then you might just be having a faulty solenoid.

Dead Battery Cells

Dead battery cells also cause your engine control unit to fail. When you leave your car in the rig over a long duration after a cell has died, it affects the ECU.

Bad Jump-Starting

Attach the jumper cables correctly every time you are jump-starting your battery. Jump starting with incorrectly attached cables will short out your engine control unit, spiking it fast.

Bad Starter

Starters have their own sensors in most vehicles, for instance, the override sensor. This sensor regulates the amount of voltage the ECU receives. A faulty starter stops the engine control unit from receiving the proper amount of voltage, causing it to malfunction and cause further problems in your car.

Repairing an engine control unit involves disassembling the unit and very vital electronic work. This may take a while, and your other option is maybe buying a new ECU as you wait for the old one to be repaired. Troubleshoot and strike off all the other potential causes before you pull down the ECU.

Fuses purposed specifically for OBD sometimes blow up for no particular reason. Inspect your fuse box for faulty fuses. Fuses are preventing the whole system from overloading, and therefore they are prone to blowouts. If you ever blew a fuse in your home, you probably have an idea of replacing a fuse.

How to Replace a Fuse

Locate the Car’s Fuse Panel

You can confirm this with the manufacturer’s manual guide. Most of them are usually found below the steering wheel on the driver’s side.

Take off the Cover of the Fuse Panel

Inside the fuse panel, there is usually a range of numbers and colors denoting different amperages. Check the reverse to cover for the fuses in your car and which parts they power.

Find the Broken Fuse

Look for any fuse that is black with a broken metal filament. Use a flashlight for clear visibility in the fuse panel.

Remove the Faulty Fuse

You can use your bare hands to remove the blown fuse from the fuse panel. Be cautious when handling the fuses since broken fuses are more difficult to extract than whole ones.

Replace the Blown Fuse

Replace the blown fuse with one that has correct amperage. Using fuse that doesn’t have correct amperage could lead to serious electrical malfunctions.

Keep Spare Fuses with Different Amperages

Keep these spare fuses in your glove box for emergencies. Just ensure that when you’re doing fuse replacements, you use a fuse with the same amperages.

Put Back the Fuse Panel’s Cover

  • Remember to put back the cover once you’re done replacing it.
  • Start the Ignition
  • Start the engine to check if your DIY project is successful.
  • If it Blows after Replacement
  • Well, consider visiting your mechanic.

Note: Always turn off your engine before attempting to remove a fuse. Do not substitute a fuse with any other object. This could lead to fires and electrocution.

Clogged Port

Over time, the OBD port gets clogged with dirt if it’s not being used. This could be the reason why you are not getting any readings. Do not use a spray cleaner whatsoever because this could get your port wet and cause more problems. Instead, use a soft cloth to wipe off the dirt from your port or blow compressed air over it. Unclog the port to remove anything that might hinder the scan from doing readings.

How to install OBD

Locate the OBD port

Find the location of the OBD port. You have to figure out the type of software you are installing in your car.

Turn the Engine off

If you install OBD when the engine is off, turning it on will activate the computer system.

Run the Device Software

The system will display the installation process on the computer screen. Run it, let it bring the interface then click ‘add’ when a prompt appears on the screen. At this point, the system is basically ready to use. Different applications on computers may bring different interfaces. The process will require you to click yes, all the way until a prompt to finish appears. It is as easy as that.

Choose the Interface

Bluetooth enabled OBD to need to initiate searches for nearby Bluetooth or to remember Bluetooth that was already detected. Go to settings and click on the set the wireless network connection. When the paired devices appear on your screen, click next until prompted to finish. Bluetooth pairing uses codes.

Enter Password

OBD software device will require you to put your password for security purposes.

OBD port has been available in cars for a long time. However, it has only just been made available for regular drivers recently. The devices and apps provide you with a much-needed insight into the state of your car way before major malfunctions occur, enabling you to prevent potentially hazardous situations.

OBD port is a crucial component in your car. Use this guide to restore it to its optimum efficiency. Call a qualified mechanic to help you fix it when you encounter a problem that is beyond your scope.

Job Guthiri is a freelance writer with 3 years of experience writing for Motorsrun and other established automobile outlets. His focus and key interests are Tacomas and maintenance. Read our Editorial Guidlines and Fact Checking process.