OBD Engine Codes, And Engine Lights, Are Only The Messenger

OBD Engine Codes, And Engine Lights, Are Only The Messenger
OBD Engine Codes, And Engine Lights, Are Only The Messenger

So, OBD Engine Codes, or a Check Engine Light, cannot be fixed, by simply resetting it or disconnecting the battery.

Eventually, the OBD Engine Codes, and the dreaded Check Engine Light, will come back! But, stay cool, the check engine light, is only the messenger.

In short, when this system identifies an issue, it turns on the check engine light and records, OBD engine codes.

So, OBD Engine Codes and Check Engine Lights, are the language your car uses, to communicate with you.

Because, it is simply doing it’s very important job. For example, letting you know that your vehicle, isn’t operating at top efficiency. Most people think, the check engine light, is only there for the vehicle’s emission system. However, this light informs the operator, when there is something wrong anywhere in the vehicles, electronic engine control system.

The OBD Engine Codes System, Basically Includes:

Consequently, your vehicle needs these and many more, to operate properly. So, to troubleshoot, repair and maintain your vehicle, you’ll need diagnostic repair information, that is specific to your vehicle.

Check Engine Light
Check Engine Light

But, with only a few basic tools, a little patience and some mechanical aptitude. Usually, you can pinpoint and repair most of these concerns yourself.

So, How Do You Read The OBD Engine Codes !

How Do I Read The Codes
How Do I Read The Codes

So, the first character identifies the system, related to the trouble code.

  • P = (Powertrain)
  • B = (Body)
  • C = (Chassis)
  • U = (Network Communication)

Then, the second digit identifies, whether the code is generic, or a manufacturer specific code.

(same on all OBD-II equipped vehicles).

  • 0 = (Standardized Code ISO/SAE) Generic (this is the digit zero — not the letter “O”)
  • 1 = (manufacturer specific OBD engine codes)

While, the third digit, denotes the type of sub system, that pertains to the Engine Code:

  1. (Secondary Air Injection System) Emission Management (Fuel or Air)
  2. (Fuel System) Injector Circuit (Fuel or Air)
  3. ( Ignition System) or Misfire
  4. (Exhaust Monitoring System) Emission Control
  5. (Idle Speed Control) Vehicle Speed
  6. (ECU) Computer & Output Circuit
  7. (Transmission System)
  8. (Transmission System)

9= SAE Reserved

0= SAE Reserved

Finally, Codes-4th and 5th, these digits are variable, and relate to a specific problem.

(OBD-II) Engine Code Reader
(OBD-II) Engine Code Reader

Code Categories:

P0100-P0199 – Fuel and Air Metering. So, these will be things like the mass airflow sensor and throttle body.

P0200-P0299 – Fuel and Air Metering (Injector Circuit). Consequently, these codes would be for things involving the fuel injectors.

P0300-P0399 – Ignition System or Misfire. So, if there was a bad spark plug or faulty coil you would see one of these codes.

P0400-P0499 – Auxiliary Emissions Controls. Above all, these are the famous (EVAP) system codes.

P0500-P0599 – Vehicle Speed Controls and Idle Control System. Furthermore, the idle air control valve and (VSS) would fall under this category.

P0600-P0699 – Computer Output Circuit. As a result, sometimes these types of codes point to a faulty computer.

P0700-P0999 – Transmission Codes. Simply lets the driver know that there is a fault, in the transmission computer unit. And, the (TCU) needs to be scanned, for OBD engine codes.

So, now you have a better idea, of what makes up, a Diagnostic Trouble Code. As a result, you can see that, every digit has its purpose. Also, you know which system, is having the problem. Consequently, just by knowing what the first few digits are.

Plugging In A (OBD) Scan Tool
Plugging In A (OBD) Scan Tool


So, OBD engine codes, are accessed by plugging a code reader, into the vehicle’s OBD port. Consequently, these codes provide you with, information about the system and conditions, under which the issue was first identified.

However, they can’t provide a clear cut solution, to the actual cause of the problem. Because, the check engine light, is only the messenger.

Thank You !

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