What is OBD-II Code P030C – Ignition A Control Signal Circuit High

OBD-II Code P030C – Ignition A Control Signal Circuit High: What You Need to Know

As a mechanic, I understand how car engines function, and I can easily diagnose problems that arise. One of the most common issues that lead vehicle owners to seek professional help is engine misfires. Fortunately, modern cars come with a built-in diagnostic system, the On-Board Diagnostic (OBD) system, that can detect potential faults and provide codes that signify specific problems. One of these codes is OBD-II Code P030C – Ignition A Control Signal Circuit High. In this article, I will explain what this code means and how you can fix the underlying problem.

What is OBD-II Code P030C?

Occasionally, your engine’s electronic control module (ECM) will record a signal that indicates the Ignition A Control Sensor Circuit is transmitting a high voltage signal for an extended amount of time. The OBD-II system will then generate the fault code P030C, and you’ll see the Check Engine light turn on.

The Ignition A Control Signal Circuit is responsible for transferring the spark signal from the coil to the engine’s combustion chamber. A high-voltage signal sent continuously to the spark plug can cause pre-ignition or engine misfires, leading to drivability problems and reduced fuel economy.

Causes of OBD-II Code P030C

Several factors can lead to the P030C code, including:

1. Damaged or faulty Ignition Coil(s): When the coil is defective, it can generate excessive voltage, producing a high-voltage spark. This high voltage can cause the P030C code.

2. Faulty Spark Plugs or Wires: Spark plugs and wires degrade over time, leading to arcing of the high voltage spark. Arcing can create a high-voltage signal to the combustion chamber, leading to engine misfires and the P030C code.

3. Malfunctioning ECM: In rare cases, the electronic control module responsible for managing the ignition signals may fail or malfunction, leading to erratic signal sending.

4. Loose or corroded connectors in the Ignition A Control Sensor Circuit: Corrosion or loose connection can create a high-voltage spark, leading to code P030C.

Symptoms of OBD-II Code P030C

If your vehicle’s computer registers a P030C code, there are several signs you may notice while driving:

1. Engine misfires: Engine misfires typically arise when a spark plug misfires or the firing order is disrupted. You may notice your vehicle shuddering or lurching around irregularly.

2. Reduced fuel economy: Misfires can cause incomplete fuel combustion, leading to decreased fuel economy.

3. Poor acceleration: If one of your car’s cylinders isn’t firing, you may notice slower acceleration.

4. Illuminated Check Engine Light: The computer will register the P030C code and flag a warning to you with the Check Engine Light illuminating.

Fixing OBD-II Code P030C

If you encounter the P030C code in your vehicle, try out the following troubleshooting methods:

1. Ignition Coil Replacement: You can replace the faulty ignition coil(s) to fix the P030C code. The new coil(s) will ensure that the engine is firing correctly and not sending high voltage signals.

2. Spark Plug & Spark Plug Wire Replacement: Worn-out or degraded spark plugs or wires can also be the cause of the P030C code. Garages can replace old spark plugs or wires with new ones.

3. ECM Replacement: The Electronic Control Module can malfunction, leading to P030C. You may need to replace the module entirely if it is beyond repair.

4. Loose Connectors/Corrosion Repair: Cleaning up loose connectors or fixing corroded circuits in the Ignition Control Sensor Circuit can resolve the P030C code.

Frequently Asked Questions:
1. What does the OBD-II Code P030C signify?

Ans. The P030C OBD-II code indicates that the Ignition A Control Sensor Circuit is transmitting a high voltage signal for a prolonged period of time leading to engine misfires.

2. Can I drive my car with the P030C code?

Ans. It is best not to drive your vehicle when the P030C code appears. Engine misfires can cause drivability problems and ultimately lead to costly repairs if not fixed on-time.

3. How much does it cost to fix the P030C code?

Ans. Pricing for repairs can vary depending on the specific cause of the P030C code. Repair costs can range from $50 to several hundred dollars.

4. Can I diagnose P030C on my own?

Ans. If you have an OBD-II scanner, you can identify the P030C code yourself. However, you may need a professional mechanic to assist with diagnosing the underlying cause of the code.

5. How often should I check my vehicle’s OBD-II system?

Ans. It is best to check your vehicle’s OBD-II system every time the Check Engine Light turns on. You should also perform routine check-ups to ensure that the system is functioning correctly.


If your engine is misfiring, encountering Code P030C, can be nerve-wracking as it can lead to reduced performance and costly repairs. However, by understanding the causes and symptoms of OBD-II Code P030C and its potential fixes, you can identify and rectify the issue quickly. Hence, detecting faults early through an OBD-II system can prevent long-term damage to the engine and the vehicle. If you are unsure of how to fix the code, do not hesitate to take it to a professional mechanic for repair.

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