Honda Foreman 500 Codes: Causes, Symptoms, and Solutions

The Honda Foreman 500 codes may include 8-2, 9-1, 21-1, etc. This either indicates that the TP sensor or the IAT sensor circuit is facing low/high voltage. Also, it may show the malfunctions of 

  • O2 sensor circuit
  • Fuel injector service
  • IACV circuit, etc. 

These are just a few examples. ATVs don’t allow to use of a scanner on them to diagnose the issues. You have to retrieve the faults from the blinks of the check engine light. Different blinks determine different meanings. 

In this guide, we will discuss some most common blink code meanings of the Honda Foreman 500. From this, you will be able to sort out the issue and determine whether you can fix them yourself or need a mechanic. 

Table: Different Honda Foreman 500 Check Engine Light Blink Codes

Before getting to the point, here is a table that shows the meaning of different blinks codes of Foreman 500.

Code NumberIssueCauses
8-2TP sensor facing high voltageTP sensor or the circuit got malfunctioned
9-1-2IAT sensor circuit is facing low/high voltageLoose connection/IAT circuit got malfunctioned
12-1Fuel injector circuit malfunctionLoose connection of fuel injector connector/Damaged fuel injector
21-1O2 sensor malfunctionLoose connection O2 sensor connector/damaged sensor
23-1O2 sensor heater circuit malfunctionHeater or circuit got damaged/Losse heater connection
29-1IACV circuit malfunctionDamaged circuit/loose connection to the connector

What Are Blink Codes in Honda Foreman?

Honda ATVs generally show the DTCs stored in the computer system through the check engine light blinking. Different blinking/flashing patterns have different meanings. These blinking or flashing patterns are called blink codes in Honda Foreman 500. 

There are two types of blinks shown in the CEL (check engine light). Long and short blinks.

Let’s make things clear with an example. 

Suppose your Foreman’s CEL shows 2 long blinks and 3 short blinks. Each long blink will be counted as 10, and the shorts will be 1. So, the blink will stand for code 23. 

Here is a visual example of blink code detection you can watch out for. 

Honda Foreman 500 Codes Meaning, Causes, Symptoms, And Way of Solutions

Here, we will discuss the blink codes meaning, causes, symptoms, and the possible way you can solve them. They are almost the same as the Honda Pioneer 1000 blink codes.

1. Code 8-2: TP sensor Facing High Voltage

You can understand code 8 when your Foreman’s CEL shows 8 fast blinking on it. This refers to the Foreman 500 getting issue with the electrical throttle positioning sensor facing higher voltage. The TP sensor monitors the engine’s air intake.

One of the reasons behind the issue is the sensor itself gets damaged. Burnt-out wiring could be another reason. 


  • You will experience poor engine acceleration
  • The ESP will not work on your Machine


  • Replace the sensor with a new one
  • Replace the wiring in case of burnt wire

2. Code 9-1-2: IAT Sensor Circuit is Facing Low/High Voltage

Code 9 can refer to both low voltage and high voltage issues in the IAT sensor. The IAT (intake air temperature) sensor record the data of the temperature of the air that the engine intakes. 

If this malfunctions, the computer system of your ATV will get the wrong information about the air temperature. This can impact the engine’s efficiency. 

The cause behind the IAT sensor voltage issue is the circuit of the sensor might malfunction. Or the sensor itself is damaged. Also, loose connections can cause this as well.


  • In this case, the engine will work normally, but you will see the CEL gives 9 short blinks


  • The circuit or the IAT sensor must be replaced if they are damaged
  • Check the connection. If a loose connection is detected, change the IAT sensor connector

3. Code 12-1: Fuel Injector Circuit Malfunction

If your Foreman’s CEL shows blink code 12, it indicates the issue with the fuel injector circuit malfunction. This can be happened due to a poor fuel injector connector. Or even the entire fuel injector might be damaged as well. 


  • Since the fuel injector can’t function, the engine will not start
  • The fuel pump, fuel injector, and ignition system will not work


  • Inspect the issue and change the fuel injector if the injector gets damaged
  • Check the fuel injector circuit and replace it if it is damaged
  • Clean the fuel injector if it gets any debris
  • Check the fuel injector connector and replace it if the connection is loose

4. Code 21-1: O2 Sensor Malfunction

O2 sensor detects the unburned oxygen in the exhaust. If it malfunctions, the engine’s electronic control unit will get the wrong oxygen data. As a result, the engine can’t get the right air-to-fuel ratio. 

It can cause due to bad wiring or the sensor damage itself. 


  • Bad fuel efficiency
  • Emission test failing due to black exhaust fumes
  • Unwanted and bothering engine noise
  • Catalytic converter failure, and many more


6. Code 23-1: O2 Sensor Heater Circuit Malfunction

The faulty O2 sensor heater circuit malfunction can cause due to the malfunctioned O2 sensor. Also, the bad wiring can be another reason as well. 


  • The engine will be running rough and will get the normal position when the exhaust becomes hot enough naturally
  • Your Foreman can experience rough idling


  • Replacing the O2 sensor heater is the solution if it gets damaged
  • Replace the bad wiring if the wiring gets damaged

6. Code 29-1: IACV Circuit Malfunction

Blink code 29, among the Honda Foreman 500 codes,  indicates IACV (Idle Air Control Valve) malfunction in your four-wheeler. It can be caused due to damaged IACV or burnt-out wiring. 


  • Your Honda Foreman will stall while running
  • The ATV will be hard to start 
  • The Foreman 500 will experience rough idling since the main function of IACV is to keep the engine’s idle speed smooth


  • Replace the valve if it gets damaged
  • Replace the burnt-out wiring 

Note: Be sure that you can DIY all solutions. If not so, you are recommended to consult a professional mechanic. They will diagnose the codes precisely and give the respective solutions efficiently. 


Some relevant questions and answers are given below for your further clarification. 

Can code issues with my Honda Foreman 500 cause damage to other systems or components of the ATV?

Yes, blink codes due to severe reasons in the ECM of Foreman 500 may cause damage to other systems or components of the ATV if not corrected.

Is it normal for my Honda Foreman 500 to have multiple codes present simultaneously?

The ECM continually monitors the ATV’s numerous systems and components and saves the code, and can show them simultaneously.


Having a basic awareness of codes is vital for keeping your Honda Foreman 500 ATV functioning properly. Whether you want to troubleshoot issues yourself or seek the assistance of a specialist.

By the way, the blink codes are not limited to our aforementioned ones. There are several codes you can face sometimes. Here we tried to give a glance at common ones so that you can sort them out quickly. 


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