Check Engine Codes

Common Check Engine Codes and When You Should Worry

Common Check Engine Codes

There’s nothing more ominous to a driver than the check engine light illuminated on the dash. Sometimes it comes on and goes back off before you can head to the mechanic, and other times it’s flashing that indicates you need service immediately.

Even the strongest person can’t help but feel a little anxiety when this light turns on, as the fear of the unknown can weigh heavy on the mind. The costs could be anywhere from a few dollars to thousands, and no one has time for their car to be out of commission in today’s busy world.

Learning the OBD II Codes

The computer in the car generates these codes. They help the mechanic quickly identify and fix the issue. It saves a lot of time and money on diagnostics when you can easily find out what’s wrong.

At Cloverdale Auto, we handle car troubles and engine codes daily, but we know that the public doesn’t have this knowledge. You can buy a machine at your local automotive store and scan it yourself, but you need to know what the codes mean. In most instances, you’ll still end up heading to your local mechanic for service.

Some codes are particular to a car manufacturer, but others will be universal. Codes are divided into four categories to help simplify things. They are as follows:

P: This code means something is amiss with the powertrain, such as the engine or transmission.

B: This code indicates that something is wrong with the vehicle’s body, such as the airbags, lights, or climate control.

C: A code that starts with C means something is amiss with the chassis. Your antilock brakes may be in trouble or the suspension system.

U: You will only see this code on vehicles after 2006. It means that the network is having communication issues. It could be the wiring or the modules, but it needs to be checked.

To further complicate matters, the second digit also has a significant meaning. Should the second number be a 1, this tells the mechanic that the vehicle likely needs further diagnostics. Things that won’t come up in these codes include low oil pressure, overheating, and a vehicle out of gas. These indicators have a separate gauge that helps to read them, so they don’t have a dedicated code.

Identifying Most Common Engine Codes

Most people recognize their car isn’t running quite right with or without the display of a check engine light. Here are some standard codes that you might observe and what they mean.

•P0411 – P0445

If you see any of these codes displayed, it means there’s an issue in the emissions control system or EVAP. Some of these codes are very benign, such as P0445. When we see this code displayed, we know that the most common culprit is a loose gas gap. However, if the P0442 comes up, it shows ups that there’s a vapor leak that could come from a faulty hose that’s cracked or loose, as well as a possible EVAP canister leak.

To diagnose these issues, we must pressurize the system and see where any leaks are present. If it’s something as simple as a gas cap, it will go off when we reset it or after so many times starting the engine. Other issues require a smoke generator to do the pressure test and find the problem.

•P0300 – P0305

Any code in this series indicates that the engine is misfiring. It can be something simple like a spark plug that’s fouling out, or it can be a vacuum leak. The computer has indicated an abnormality in the pace of the crankshaft while the engine is running. Sometimes, the fuel-to-oxygen ratio is off, or there’s a dirty fuel injector. It requires some diagnostic work, but we recognize that a P0301 is likely spark plugs that need to be changed, and so on.

•P0171 – P0174

Codes within this category are usually not so cut and dry to diagnose. It could indicate that the EGR valve is malfunctioning, or there’s a Mass Airflow sensor issue. Sadly, we often must do more investigation to find the diagnosis. Codes in this range mean the engine has a lean-running condition, and we need to pull out a more advanced scanning device to help uncover the mystery.

•P0420 – P0430

If the vehicle uses the OBD II standards, these codes often indicate a problem with the catalytic converter. We know that these codes usually mean costly repairs. It could be a 02 sensor, but it could mean something like a coolant leak.

Over time, the catalytic converter can become damaged. The damage can occur from an engine burning too much oil or a coolant leak somewhere within the system. This converter is essential to the vehicle as it eradicates toxic engine-exhaust pollutants from being released into the atmosphere. It’s illegal to drive without one, as it harms the environment.

•P0133 – P0141

The common culprit with these codes is a 02-sensor issue. The computer has indicated that the fuel metering needs to be adjusted, and it’s likely a failure from this sensor. The 02 Sensor will become worn out or carbon-fouled over time, so it causes the engine to misfire, much like a worn spark plug.

Getting Your Car Serviced

Seeing the check engine light is often scary, as you know it will likely mean a trip to the mechanic. However, at Cloverdale Auto, we try to get your vehicle in and out of service as soon as possible. We understand the inconvenience of a mechanical issue, so we strive to ensure our customers get fast and professional service at reasonable prices.

Cloverdale Auto Service