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Common Car Diagnostic Codes and What To Do About Them

Diagnostic Trouble Codes 101

Your vehicle’s on-board diagnostic system (OBD-II) provides diagnostic trouble codes to notify drivers of any issues. The codes correspond to a problem detected in the vehicle and the car stores the codes in its memory. Technicians at auto repair shops such as Ken Van Damme’s Automotive can scan your car’s memory to read the codes to help diagnose and repair any problems.

OBD-II Trouble Code Categories

There are four main categories of OBD-II trouble codes, and they’re identifiable by the first letter of the code:

Body Codes (B-codes)

The B-codes category covers any issues and functions inside of the passenger compartment of the car. Functions in this category are typically associated with comfort, assistance, convenience, and safety.

Chassis Codes (C-codes)

The C-codes category covers any issues related to functions outside of the passenger compartment, such as brakes, steering, and suspension.

Powertrain Codes (P-codes)

Powertrain codes typically cover functions within the engine, transmission, and drivetrain accessories.

Network & Vehicle Integration Codes (U-codes)

The U-codes category covers any functions shared among computers and other systems within the vehicle.

The Difference Between General and Manufacturer-Specific Codes

While many codes are general and stay the same across different makes and models of vehicles, some trouble codes are specific to the manufacturer.

General OBD-II Codes

If the trouble code starts with a 0, it’s a general code. General codes are common to all cars that are manufactured to OBD-II standards.

Manufacturer-Specific OBD-II Codes

Manufacturer-specific OBD-II codes are identifiable as codes with a “1” as the first digit. However, some manufacturer specific codes start with a 2 or 3 such as B2xxx codes and C2xxx codes. One notable exception is P2xxx codes, which are generic, and P3xxx codes, which are manufacturer specific.

Common Car Diagnostic Codes

We’ve put together a list of some common car diagnostic codes that may come up when a technician scans your vehicle, and what will likely be the response to that code.

P0420: Catalyst System Efficiency Below Threshold and Other Catalytic Converter Codes

The error code P0420 indicates an issue with the catalytic converter. Your vehicle’s catalytic converter works to reduce emissions, but sometimes the sensors are faulty. Like most diagnostic codes, multiple issues within the vehicle’s exhaust system can cause this error code. If you see error code P0420, take your car into Ken Van Damme’s Automotive in Portland to have their highly-trained and experienced technicians diagnose and repair the problem.

P04976: Evap Flow During Non-Purge Condition and other EVAP System Codes

If a technician scans your vehicle’s memory and the code P04976 pops up, something is likely wrong with the vehicle’s EVAP system. A car’s EVAP system helps contain dangerous fumes let off by gasoline, and keep them from being released into the atmosphere. The error code comes up if the vehicle detects flow in the EVAP system at a point when it shouldn’t. There aren’t a lot of symptoms associated with this error code other than a check engine light, but it’s important to have a trained technician at Ken Van Damme’s Automotive take a look and ensure the vehicle’s EVAP system is working properly. Some causes of EVAP system problems may affect other areas of your vehicle if left unchecked. Other common diagnostic codes related to the car’s EVAP system include P0411, P0440, P0442, P0446, and P0455.

P0171: System Too Lean Bank 1 and Other Oxygen Sensor Codes

Another common diagnostic code includes P0171 and other related oxygen sensor codes. The error code P0171 indicates a problem with the air/fuel ratio leaving the cylinders of the engine. If the mixture is too oxygen-rich, the vehicle’s engine control module sends the error code to the vehicle’s computer. While motorists may not notice any symptoms because of this code, sometimes the vehicle may have a rough idle, problems accelerating and reduced power. Multiple issues could be causing this error code, so it’s important to have an ASE-certified technician, such as the knowledgeable staff at Ken Van Damme’s Automotive, look at your vehicle and determine the best course of action. Other common oxygen sensor codes include P0172, P0173, P0174, and P0175.

P0300: Random Misfire Detected and Other Engine Misfire Codes

The diagnostic code P0300 indicates that one of the vehicle’s cylinders misfired. Many things could cause a misfire, including problems with the car’s fuel injectors, oxygen sensors, or camshaft position sensors. However, it’s also possible that the code has appeared due to a problem with the spark plugs or the car’s computer, so you must take the vehicle into Ken Van Damme’s Automotive in Portland for diagnosis and repair. While you may not have any symptoms related to the trouble code, your vehicle may have difficulty starting or problems with the engine slowing down or pausing. Don’t wait on this one, as engine trouble can lead to costly repairs.

P0401: Insufficient Exhaustive Gas Recirculation (EGR) Flow

This code indicates an issue with the vehicle’s EGR system. The EGR system is responsible for controlling combustion temperatures and the output of nitrogen oxides. While you may not notice any symptoms of this trouble code other than the check engine light, some drivers may notice lower fuel economy, rough idling, or pre-ignition knocking or pinging. Multiple issues with your vehicle can trigger this error code, including a clogged catalytic converter, electrical problems within the EGR’s circuit, problems with the engine’s computer. Have a trained technician at Portland’s Ken Van Damme’s Automotive take a look if you see this code.

How Can Ken Van Damme’s Automotive Help?

If your check engine light is on and you’ve noticed one of the above trouble codes, don’t worry. The experienced team at Ken Van Damme’s Automotive can diagnose and repair the problem for you. With over fifty years of experience in the automotive repair business, owner Ken Van Damme aims to provide the best car repair in Portland with honest, straightforward estimates. Call today to set up your appointment!

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Common Car Diagnostic Codes and What To Do About Them

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