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The Simple Guide to The Check Engine Light

Picture this, you’re driving your car and suddenly there is a bright yellow light that starts flashing on your dashboard. If you’re like most drivers, you have no idea that the light is the check engine light. A lot of drivers tend to ignore the check engine light, either because they don’t know what it means or because it could mean a variety of things ranging from extreme to mild.

The check engine light is an indication that there is a problem with your vehicle, meaning you really should get it fixed as soon as you can regardless of the suspected severity.

What could cause the check engine light to come on?

  • Some of the main causes of the check engine light include:
  • The oxygen sensor has failed and needs to be replaced
  • You need new spark plugs or plug wires
  • It’s time to replace the Mass Airflow Sensor (MAF)
  • Your catalytic has failed and needs to be replaced
  • The gas cap has come loose, is damaged, or missing

It’s important that you don’t ignore the check engine light when it comes on because you run the risk of your vehicle breaking down.

Is check engine light serious?

Is it serious?

The check engine light is one of the most misunderstood signals your car gives because it has various meanings. It may turn out to be a very simple problem with an easy fix or it could be warning you about a very serious and potentially engine damaging issue.

The severity of the signal is expressed with either a flashing or constant light. When this check engine light is flashing it means that your car issue is very serious. When this happens it is recommended that you pull over and have it towed to a mechanic for a diagnostic check. A steady illuminated check engine light means that the problem is less significant but you do require service.

How long can you drive with check engine light on?

It’s important not to panic when the check engine light comes on while you’re driving. Remain calm and look at whether the car is driving differently than normal. If everything is normal you can keep driving, but you should still take it straight to a mechanic to get the problem checked out and fixed.

check engine light on

What are common diagnostic codes for check engine light?

The diagnostic codes for check engine lights are divided into 4 categories, which are:

  • Powertrain (P)
  • Body (B)
  • Chassis (C)
  • Network Communications (U)

These codes are divided further into 2 main groups, which are:

  • Enhanced or specific (1 comes as the 2nd digit)
  • Generic or global (0 comes as the 2nd digit)

The most common diagnostic codes for check engine lights are:

  • Codes: P0171 – P0175 → Deals with sensing your oxygen levels
    • P0171: This code tells you that your system is too lean, meaning that your engine is receiving either too little or too much air.
    • P0172: This code means that your system is rich, indicating that there is too much gasoline and not enough oxygen in the engine.
    • P0173: This code gets triggered by the engine control module when it senses that the air to fuel is either too learn or too rich. The engine control module has the ability to balance this out, however, if this compensation is too much, this code will be triggered.
    • P0174: This code tells you that there is an under reporting in your Mass Air Flow Sensor. So basically, your sensor is reporting that much less air is coming to the engine than actually is.
    • P0175: This code means that your system is rich, indicating that there is too much gasoline and not enough oxygen in the engine. This can occur for a variety of reasons, so a mechanic will need to identify a specific cause for the code being triggered.
  • Codes: P0300 – P0305 → Deal with engine misfires
    • P0300: This code will be triggered when you have an engine misfire that is related to multiple cylinders.
    • P0301: This code indicates an engine misfire in cylinder 1.
    • P0302: This code indicates an engine misfire in cylinder 2.
    • P0303: This code indicates an engine misfire in cylinder 3.
    • P0304: This code indicates an engine misfire in cylinder 4.
    • P0305: This code indicates an engine misfire in cylinder 5.
  • Codes: P0411, P0440, P0442, P0446, P0455 → Deal with the evaporative system
    • P0411: This code will appear when you have a problem when the secondary injection system has an incorrect flow detected.
    • P0440: This code will appear when there is a leak in the fuel tank vapor system or a vapor pressure sensor malfunction.
    • P0442: This code means that there is a problem with the evaporative emission control system. This code typically appears in tandem with other evaporation system codes.
    • P0446: This means that the evaporative emission control system vent circuit is malfunctioning.
    • P0455: This code means that there is a leak in the emission control system. A good place to check first is the gas cap. Another common explanation for this leak is a bad vent control valve.
  • Code: P0401→ Deal with exhaust gas recirculation
    • P0401: This means that the exhaust gas recirculation system flow is not sufficient.
  • Codes: P0420, P0430 → Deal with the catalytic converter
    • P0420: This code tell you that you catalytic converter is not functioning at max efficiency, typically because it needs to be replaced or there is a problem with the oxygen (O2) sensors.
    • P0430: This code is more general, it indicates that there is a problem in the catalyst system. Since this code is very general, it is typically also seen with misfire codes and oxygen sensor codes.

 

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