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The On-Board Diagnostics Is In

Beyond your steering wheel lies the dashboard, called the On-Board Diagnostic system or OBD, that shows detailed information on your vehicle’s operation and performance. In short, it’s a uniformed system that allows the vehicle to monitor and communicate via the car’s internal computer system or ECM/PCM. OBD is essential in monitoring major engine functions, electrical condition, and measuring vehicle emissions. A qualified technician utilizes the vital information that is stored by OBD to help determine what mechanical or electrical processes have failed in order to repair a vehicle.

What Is OBD?

The Check Engine Light is Part of the OBD

On-Board Diagnostic System CheckSensors within the vehicle’s engine monitor and provide information to the vehicle’s computer to keep it performing optimally. The engine itself is a complex component and has many internal operations that work together in order to keep the vehicle moving forward. The internal computer and its sensors collect data and tell each system how to operate. For example, the system observes and determines how much fuel should be injected into the cylinders, the timing of the ignition, spark plugs, and fuel efficiency. When something doesn’t operate as it should or doesn’t comply within the set of programmed parameters, the computer triggers the check engine light to turn on and tells the vehicle to adjust its operation so that you can continue driving, allowing you to get to an automotive repair center for attention. During this time, you may observe a change in acceleration, a reduction in fuel efficiency, rough idling, or other symptoms. It’s important to note that driving for an extended period of time with any lights illuminated on the OBD, can cause further damage resulting in costly repairs. If at any time the lights are flashing on the dashboard, avoid driving the vehicle and take it to a trusted technician immediately for inspection.

Common Codes

When your vehicle arrives at a service center, the technician will begin testing the system using a specialized computer scan tool. Once the technician determines which codes are responsible for the trouble, they’ll be able to investigate the cause of the problem. Here are five of the most common codes:

  1. P0171 – P0175 – The Oxygen Sensor. This sensor is responsible for monitoring the amount of oxygen in the exhaust so that the computer is able to adjust the fuel and air combination for the engine to perform efficiently, increase fuel economy, and decrease emissions. Associated symptoms include poor gas mileage or stalling.
  2. P0300 – P0305 – Engine Misfire. Misfires are the result of dysfunctional cylinders. Misfires detect the amount of fuel each cylinder requires; not needing fuel means there little or no spark. Associated symptoms include shaking and vibration while idling and poor fuel economy.
  3. P0411, P0440, P0422, P0446, P0455 Evaporative System. The evaporative system is responsible for containing and preventing vapors from being released into the air. The system reuses the vapors contained by returning them back to the engine for burning. Associated symptoms include rough idle and difficulty starting. Often, a loose gas cap can be responsible for prompting this code. The EVAP system also includes the vacuum sensor, purge and pressure valves, vent hoses, and the charcoal canister.
  4. P0401- Exhaust Gas Recirculation (EGR). The EGR controls the engine’s release of dangerous emissions by recirculating the engine’s exhaust back into the engine cylinder. This also cools the cylinder temperatures down, reducing emissions. The computer regulates when to open and close the valves to recirculate the exhaust. Problems occur when carbon builds up within the system. This is often due to lack of oil changes, infrequent driving, or carbon as a byproduct of gasoline. Associated symptoms include a reduction in power, acceleration, and decreased fuel efficiency.
  5. P0420, P0430 – Catalytic Converter. The “cat” converts pollutants and harmful gases in the exhaust into safer gases for release out and away from the vehicle. The cat generally lasts for a significant amount of time. Unburned fuel is most often responsible for its failure which is the result of an engine misfire and low compression. The longer you drive your vehicle with the engine light on, due to a misfire code, the greater the possibility of damaging the cat. A car that burns an excessive amount of oil can cause a cat to fail. Associated symptoms include increased tailpipe emissions from burning oil or leaking coolant.

Though it’s fortunate we live in times where vehicles are intelligent enough to indicate when something is wrong, with light providing a general idea as to where the problem lies and the scan tools to decipher them, they’re unable to pinpoint the exact problem. This is a common misconception for many vehicle owners. Additional labor and testing of a variety of components are often required to isolate the issue responsible for the code. Perhaps in the future cars will be able to indicate what and where repairs are required, but for now, basing repairs on symptoms, codes, and diagnostics is how a technician is able to repair your vehicle.

At Mac’s Automotive Service and Radiator Repair, our ASE Certified Technicians specialize in performing diagnostics with the help of your OBD to help clear your trouble codes, including the check engine light to get you back on the road as swiftly as possible! When the check engine light comes on in your car, there’s no reason to panic when you have Mac’s on your side! Stop by any of our convenient service center locations or schedule an appointment to have your diagnostic codes scanned and if needed, repaired.

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