C1234 code: What is the meaning and reason for this problem?


A car is a mandatory form of transportation nowadays. Many people own this vehicle to save some time. Driving a car is easy, but taking care of it is tricky. Finding the problem before any accident is entirely tough for ordinary people. For this reason, an Onboard diagnostic scanner attaches to every vehicle. This scanner shows you if the car faces any problems when driving it. Just like that, when you encounter a problem with the right front wheel speed sensor, the input signal is somehow missing, then you can find the trouble code C1234 on the car screen.

Meaning of the code C1234: 

 The problem of the trouble code C1234 is related to the Anti brake system or ABS control module. When the ABS module receives the reading of the wheel speed from the wheel speed sensor, it processes this information to find if an ABS event is necessary. The wheel speed sensor also detects the magnetic field of the sensor ring o that it passes the face of the active wheel speed sensor. The ABS receives a signal which generates from the active wheel speed sensor. Here two wires and a connector mainly connect the wheel speed sensor to the ABS module. After the ignition is turned “ON” position, the ABS runs a self-test and carries a reference voltage to all-wheel speed sensors through the circuitry. It is mainly used to determine if this circuit is functional or not.

After that, the ABS module continuously monitors and compares the rotational speed of every wheel. The ABS also finds this when it detects an impending wheel lock and modulus brake pressure to the proper brake caliper. This occurs when the hydraulic control unit or HCU triggers to open and close the attached solenoid valve. Once the affected wheel gains the average speed, the ABS returns the solenoid valves to their normal state, and standard braking resumes working.

Possible reasons:

There are some common reasons behind the trouble code C1234. Those are:Wheel Speed Sensor

  • There is a fault in the right front wheel speed sensor,
  • The harness of the right front wheel speed sensor is open or shorted,
  • If there is any poor or damaged electrical connection in the right front wheel speed sensor.
  • If your car has some dirty il, it also shows the same problem code.
  • Problem with the fuel position


You are learning about this type of problem’s symptoms to help you fix the advanced issue stage. And there are also some common symptoms you can notice while your car faces the issue C1234. Like:

  • The warning light of ABS or anti-brake system is “ON.”
  • Illuminated engine light.

Diagnosis process of the C1234 error code

After you notice the symptoms, you need to ensure the problem of this code. For this reason, you need to run a short diagnosis process. Like:

  • Check the harness of the right front wheel speed sensor properly.
  • Check all the wiring and connectors of the anti-brake control module,
  • Visually inspect all the details of the ABS control module.

Fix the OBD code C1234:

After noting all the possible issues behind the trouble code C1234, it’s time to repair it. First, check whether the gas cap is installed tightly; sometimes, this also happens to trouble the right front wheel speed sensor. If you find any problem with a harness, solve the issue. Then check all the wiring and connector of the control module. If you find any damaged component or broken, bent, pushed out, or corroded connector pin, repair it. If it’s not in a repairable position, remove it and place a new one. I think this little step can easily help you quickly fix the issue.


The trouble code C1234 is related to the ABS control module. And in the world, significant accidents happen only for the failure of the brake system. This code C1234 is not an important issue, but if you don’t repair it early, it can create a big lousy situation in the future. If you cannot fix the issue yourself, you can consult with a professional. A technician needs around one hour to find the problem. They use the TSB manual to find the problem in a bit of time. This book contains all details about your car. And the manufacturer has also attached the reason and solution for this type of issue. And that is why if you use it, you can do it by yourself and save some money and time. Also, try to clean your gas tank for further this type of trouble.

Kevin Nicholas is an automotive technician who is a genius at software and hardware-related issues. He manually tested more than a hundred OBD scanners and gave his honest opinion on whether the device was worth the money or not. His in-depth OBD review articles help people choose the right product, whether it is a European, American, or Asian vehicle. He completed his Automotive Specialized Training Course at Universal Technical Institute and has more than 15 years of experience in the field.

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