P2305 Code: Ignition Coil “B” Secondary Circuit

You might’ve encountered a P2305 code while using a scan tool to diagnose your vehicle and wondered what to do. OBD-II codes are fairly complicated and require a certain level of auto repair knowledge to fully understand and address. We’ve compiled the most important information about this diagnostic trouble code (DTC) so you can learn more about it.

What Does the P2305 Code Mean?

P2305 stands for “Ignition Coil ‘B’ Secondary Circuit.” It’s a generic powertrain code that can show up in various makes and models equipped with OBD-II.

A P2305 code can register in a vehicle’s powertrain control module (PCM) if the PCM detects an abnormal voltage condition in the ignition coil’s secondary circuit. This code is usually  accompanied by an illuminated malfunction indicator lamp.

The letter “B” can refer to the ignition coil’s secondary control circuit with the “B” designation. The location of ignition coil “B” might vary depending on the vehicle’s model, but it usually refers to the ignition coil at cylinder number two.

On a modern vehicle, the ignition coil’s secondary circuit usually consists of the spark plug and secondary windings inside the coil-on-plug ignition coil. Meanwhile, the ignition coil’s primary circuit includes the primary windings inside of the coil-on-plug ignition coil, an engine RPM sensor (usually the crankshaft position sensor), the powertrain control module (PCM), and corresponding circuitry. The ignition switch supplies battery power to the primary circuit.

If the PCM detects a problem with the ignition coil “B” circuit, it will store code P2305 in memory.

You may also watch this video to understand how ignition coil works:

Note: The definition of code P2305 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database to learn how to fix a P2305 code.

What are the Common Causes of the P2305 Code?

The problems that trigger a P2305 code can be caused by a number of factors. Here are some of the most common causes of issues that set a P2305 code.

• Faulty ignition coil
• Circuit issues, such as damaged wires and poor connections
• Worn-out spark plugs
• An issue with the PCM, such as software in need of an update

What are the Common Symptoms of the P2305 Code?

If a P2305 code is accompanied by other DTCs, you might observe symptoms that aren’t listed here. However, if your PCM is only storing a P2305 code, your vehicle might exhibit the following symptoms.

• Illuminated check engine light
• Misfiring
• Poor engine performance
• Reduced fuel efficiency

How to Diagnose the P2305 Code

The diagnostic procedure for a P2305 code might differ from vehicle to vehicle. What might work to resolve a P2305 in a Dodge might not work for a Jeep. You’ll have to consult a repair manual or database if you plan on troubleshooting this code yourself. The following video will give you an idea of how you might address this DTC, but you’ll still need to do some research on your vehicle. If you don’t have the required skills to troubleshoot a P2305 code, it’s best to leave it to a professional.

How to Fix the P2305 Code

A P2305 code can indicate one or several problems with your vehicle’s system. There are multiple ways to fix the problems related to this code, but you have to be skilled and knowledgeable enough to perform the necessary diagnosis and repairs. You can try searching for technical service bulletins that are related to your problem. Some of them are readily available online. You can use this information as a reference when repairing your vehicle.

You can also look for Chilton repair manuals and sign up for ALLDATA’s single-vehicle subscription service for detailed information on your specific vehicle.

If you don’t have the confidence to do some DIY repairs, you can also hire a mechanic to do them for you. They can run tests using their scan tools and do the appropriate repairs.