OBD Codes (Check Engine Light) Trouble Codes Explained

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OBD Codes (Check Engine Light) Trouble Codes Explained

Cars are smart these days. Your car can now use codes to tell you what’s wrong instead of having to guess. But now the codes are confusing. Our technicians at Dakota Ridge Auto in Littleton can get the OBD (check engine light) trouble codes explained for you.

When there is something wrong with your vehicle, its sensors will generate auto diagnostic codes to help us know where to look for trouble.

The DTC (Diagnostic Trouble Codes) point us in the right direction, but we still have to figure out exactly what is wrong. But we’re going to give you what system the code is pointing to, so you will know generally what could be wrong.

Many codes are general, while others are manufacturer codes that are specific to your car or truck. The manufacturer codes will need a professional to understand.

With only a few exceptions, these check engine light codes will pertain to vehicles built from 1996 until now. They contain letters and numbers, each of which has a specific meaning. Let’s break it down.

1st Digit of the Code:

B is for Body

C is for Chassis

P is for Powertrain

U is for Network

2nd Digit of the Code:

0 is for SAE which is generic

1 is for MFG (Manufacturer Specific Codes)

3rd Digit of the Code:

1: Fuel and Air Metering. Trouble with the mass airflow sensor and throttle body.

2: Fuel and Air Metering (Injector Circuit). Problems with fuel injectors.

3: Ignition System or Misfire. A bad spark plug or faulty coil.

4: Auxiliary Emissions Controls. EVAP system codes.

5: Vehicle Speed Controls and Idle Control System. Check the idle air control valve and VSS.

6: Computer Output Circuit. Possibly a faulty computer.

7-8: Transmission Codes. To find the fault, scan the transmission computer (TCU) for its code.

4th & 5th Digits of the Code:

This is a two-place fault code, numbered 1-99, that points to a more specific issue related to the system indicated in the 3rd Digit.

Types of Codes

There will be two types of OBD codes (DTC) that apply to OBD II. Type 1 codes can create severe damage, fast. You need to pay attention to them right away. Type 2 needs to be looked at but not with the urgency of Type 1 codes.

Type 1

  1. Relates to emissions, things like EVAP codes.
  2. Will illuminate the MIL after one failed driving cycle.
  3. Gives a trouble code freeze frame after one failed driving cycle.

Type 2

  1. Gives emissions OBD codes that aren’t causing lots of pollution.
  2. Sets a pending trouble code after one failed driving cycle.
  3. Clears a pending trouble code after one successful driving cycle.
  4. Check engine light turns on after two consecutive failed driving cycles and saves a freeze frame after two consecutive failed driving cycles.

A car’s trouble codes should not be ignored. Our technicians at Dakota Ridge Auto in Littleton can get the OBD (check engine light) trouble codes explained for you, as well as provide a full diagnosis of what’s going in with your car. Once we figure out the source of the problem, we’ll get it repaired and get you back on the road. Contact us today or come by the shop for your check engine light check.

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