Error Code P2305 is defined as Ignition Coil “B” Secondary Circuit. This code is caused by a problem in the wiring or the ignition coil.

This error code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, especially those made since 1996 up to present. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.


Error Code P2305 means there’s a fault within the ignition coil B secondary circuit. The ignition coils work by ramping electricity up from the battery, providing the spark needed to ignite the fuel. When this component malfunctions, the Check Engine light will be triggered, and the code will be registered to the memory of the vehicle. Also, this code will set the vehicle to Failsafe mode, and it will remain in effect until the error is fixed or the vehicle is back to normal operation.

This error code can also be seen with misfire codes and other codes related to driveability problems.

Common Symptoms

As said earlier, this code activates the Check Engine light and registers the code to the memory of the vehicle. Since it puts the vehicle into failsafe mode, it can also cause drivability issues to keep the engine from further damage. Other common symptoms include:

  • Engine misfires
  • Engine running rough
  • Engine lacking power

Possible Causes

Many factors lead to this error code, such as:

  • Intermittent connection caused by corrosion or poor electrical connection
  • Failed ignition coil 2
  • Open or short in the Ignition Coil 2 wiring harness
  • Failed spark plug

How to Check

Mechanics diagnose this code by using a scan tool into the DLC port and checking for other codes present in the PCM. They will take note of all the existing codes and their associated freeze frame data before clearing the codes for a fresh start.

Then, they will take the vehicle for a test drive and put it into similar circumstances when the freeze frame data was stored.

Next, they check for damages or signs or wear and tear in the spark components, as well as test the spark plug coil and all its wirings.

Next, they will use the scan tool to monitor the operation of the secondary ignition coil circuit.

They will check the coil for resistance.

Lastly, they will inspect the spark plug if it’s working properly, and look for signs of damage.

How to Fix

Repairs for this code are as easy as its diagnosis. Obviously, as with other error codes, it requires a thorough diagnosis to be fixed. Typical repairs include:

  • Replacement of faulty spark plugs
  • Repair or electrical connection
  • Repair of open or short in the ignition coil harness
  • Replacement of faulty ignition coil

Before replacing any components, it is important to inspect and test them thoroughly to avoid unnecessary and expensive repairs. For diagnosis, it is important to check the spark plugs and look for signs of corrosion and wear and tear.