Fault code P2304 is called “Ignition Coil “B” Primary Control Circuit High” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P2304
This Diagnostic Trouble Code (DTC) is a generic code. Error P2304 is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.
If your vehicle has stored this error code accompanied by a Malfunction Indicator Lamp (MIL). This means that the Powertrain Control Module (PCM) has detected an abnormal voltage in the ignition coil “B” primary control circuit.
The primary ignition coil circuits are the wires that supply voltage to the coil from the battery. The voltage is supplied through fuses, relays and various other sources.
Secondary ignition coil circuits include the ignition coil as well as the spark plug wires. Which are responsible for transferring the high energy spark from the coil to the spark plug.
Typically, the ignition coil is supplied with battery voltage as well as ground. When the ground signal is interrupted, the coil fires a high-energy spark that exits at the end of the spark plug.
If the voltage to the ignition coil is excessive, normal spark discharge will not occur and fuel cannot be ignited in the cylinder. The PCM will record error P2304 in memory and illuminate the instrument panel warning light.
Symptoms of vehicle malfunctions
The main signal that an error P2304 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
- Other related fault codes may also be present.
- The motor may run, but with reduced performance (power drop).
- Twitching as well as ignition skips.
- Increased fuel consumption.
- Fuel injector operation for the affected cylinder may be disabled by the PCM.
The symptoms that occur when the P2304 fault code occurs usually require immediate attention. If it occurs, it is unlikely to cause serious drivability problems, but the cause should be diagnosed as soon as possible.
Factors that can cause this error code
The error code P2304 can mean that one or more of the following problems have occurred:
- Faulty ignition coil.
- Bad spark plugs duster or wire.
- Broken or shorted wiring or wire connectors.
- Defective relay or blown fuse.
- Camshaft or crankshaft sensor may be defective.
How to fix or reset OBD-2 code P2304
Some suggested steps for troubleshooting and fix the error code P2304:
- Make sure that the electrical connection in the coil connector is good.
- If there is a problem with the motor, turn it off and disconnect the cables relating to coil “B”. Then start the motor with the cables disconnected and use a voltmeter. It should show a range of 5 to 20 Hz, if this range is not present, replace the ignition coil.
- If there is no signal from the PCM in the ignition coil circuit, leave the coil disconnected and check the circuit wires at the ignition coil connector. Significant voltage means a short. You need to locate it and make the necessary repairs.
- If there is no voltage in the driver circuit, disconnect the connector from the PCM. And check the continuity of the driver circuit between the powertrain control module (PCM) and the coil. If there is no breakage, it indicates a ground fault. Fix the problem.
- If there is a breakage, check the resistance between the ground and the ignition coil connector. The result should be infinite resistance. If not, correct the ground fault in the coil driver circuit.
Diagnose and repair of problems
When starting to correct error P2304, try to move and test the wiring on the coil and along the wiring harness. If manipulation of the wiring causes ignition skips, correct the problem with the wiring. Check that the contact in the coil connector is secure. Make sure the wire bundle is not rubbing against anything, repair if necessary.
If the engine is experiencing interruptions similar to ignition skips, stop the engine and disconnect the “B” coil wire connector. Then start the engine and check the driver signal on the coil.
Use a voltmeter mounted on the AC scale in hertz. See if there is a reading between 5 and 20 Hz, this indicates that the driver is working. If the reading is different, replace the ignition coil.
If there is no frequency signal from the PCM in the ignition coil driver circuit, leave the coil disconnected. Check the DC voltage in the driver circuit, at the ignition coil connector. If there is significant voltage on this wire, there is a short somewhere, find the short and correct it.
If there is no voltage in the driver circuit, turn off the ignition. Disconnect PCM connector and check for continuity between PCM and coil. If there is no continuity, repair the circuit breakage or short.
If an open circuit is present, check the resistance between the ground and the ignition coil connector. The resistance should be infinite. Other readings indicate a short, correct the ground fault in the coil driver circuit.
If you find that the engine is skipping ignition, the coil is triggering correctly, but code P2304 keeps showing up. There is a possibility that the PCM coil control system may be defective.
On which vehicles does this problem occur most frequently
Fault code P2304 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Ford (Focus)
- LADA (Granta, Kalina, Priora, Vesta)
- VAZ (2112)
Fault code P2304 can sometimes be found with other errors. The most common are the following: P0302, P0335, P2300, P2301, P2302, P2303, P2305.