P2302 – Ignition coil A, secondary circuit – malfunction


By Reinier (Contact Me)
Last Updated 2022-03-25
Automobile Repair Shop Owner

CodeFault LocationProbable Cause
P2302 Ignition coil A, secondary circuit - malfunction
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Wiring, ignition coil

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What Does Code P2302 Mean?

OBD II fault code P2302 is a generic trouble code that is defined as, “Ignition coil A, secondary circuit – malfunction”, and is set when the PCM (Powertrain Control Module) detects a failure in or malfunction of the secondary circuit of the ignition coil labeled “A” on the affected vehicle. Note that while on most applications, the ignition coil labeled “A” is the coil on cylinder #1, there are exceptions to this rule. Therefore, it is recommended that reliable service i9nformation for the affected vehicle be consulted to identify ignition coil “A” correctly.

NOTE: In the context of code P2302, the word “circuit” actually refers to the secondary windings of the coil, as opposed to a regular circuit that powers an electrical consumer like a light or a blower motor.

Regardless of whether an ignition coil provides an ignition spark to a single cylinder, as in the case of a COP coil (Coil over Plug, aka pencil coil), or two/multiple cylinders via separate plug leads, all ignition coils work in the same way. In its simplest form, an ignition coil is a transformer that converts a low voltage into a voltage that is high enough to create an ignition spark across the electrodes of a spark plug. Here is how this works-

When an ignition coil receives an ignition trigger current, this current creates a magnetic field in a set of copper wire windings. One end of the windings is connected to the input or trigger signal, while the other end s connected to a central iron core that runs through both the primary and secondary windings. The other end of the iron core connects to the sparkplug- either directly, or via a plug lead.

On all applications, the ignition trigger signal is fed into the primary winding for only a few microseconds, with the actual time depending on both the ignition coil design and the programming of the ignition driver circuits in the PCM.

This period is known as the coil ramp-up time or dwell angle, and varies between applications and coil designs. Nonetheless, this time is strictly controlled by the PCM, which removes the ground connection to interrupt the primary ignition trigger signal. When this happens, the magnetic field that had been induced in the primary windings collapses extremely rapidly, which then induces a magnetic field in the secondary windings.

Note, though, that the strength of the second magnetic field depends entirely on the ratio between the number of winding in the primary coil and the number of windings in the secondary set of winding. For instance, if the primary windings have say, 100 turns that produce a current of 400 volts when the magnetic field collapses, and the secondary windings have say, 1000 turns, the ratio between the two sets of windings is 1:10. Therefore, the secondary windings will produce a current of 40 000 volts when the secondary magnetic field collapses, which then creates the ignition spark when this current ionizes the air in the gap between the spark plug electrodes.

We need not delve into the complex laws of electricity that govern the relationship between electricity and magnetism here, beyond saying that magnetism and electricity cannot exist independently of each other. Therefore, the PCMs on all spark-ignition applications look for the presence of induced oscillations in the discharge waveform when the secondary magnetic field collapses. These oscillations are the result of induced “kick-back” currents that diminish gradually as the secondary magnetic field dissipates, and the PCM interprets these oscillating currents as confirmation that an ignition spark had been delivered to the cylinder via the sparkplug.

As a practical matter, most PCMs can detect the relatively low-intensity magnetic field that the primary windings generate, but since this field is not strong enough to generate an ignition spark, the PCM specifically looks for a feedback signal  (in the form of induced oscillating kick-back currents) that the secondary windings produce when the high-intensity secondary magnetic field collapses.

Thus, the PCM interprets the absence of a feedback signal as the absence of an ignition spark, but since only the secondary windings can produce the feedback signal, the PCM will set trouble code that relates to a failure of the secondary windings, as opposed to setting a code that relates to a general failure of the ignition coil. This distinction is important from a diagnostic perspective because it (largely) eliminates faults and defects in the low voltage primary ignition circuit(s) of the affected ignition coil as likely or probable causes of code P2302.

Where is the P2302 sensor located?

This image shows the location and arrangement of four individual COP (Coil over Plugs) ignition coils on a four-cylinder engine. Note that on some engine designs, the coils may be hidden or obscured by cosmetic engine covers, which must be removed to gain access to the coils.

Note also that coil “A” is usually associated with cylinder #1, which is always located furthest away from the transmission on engines with an in-line configuration. On V-type engines, however, cylinder #1 is usually (but not always) located nearest the front of the vehicle in the bank of cylinders on the driver’s side of the engine. Thus, since this position is not uniform across all V-type engines, it is recommended that the position of cylinder #1 be verified with reliable service information for the affected engine.

What are the common causes of code P2302?

Common causes of code P2302 could include one or more of the following-

  • Mechanical damage to the coil caused during routine repairs and/or servicing, but note that such damage may not be visible during a visual inspection
  • Broken, loose, or poor connection between the ignition coil and the sparkplug
  • Defective or unsuitable ignition coil
  • Excessively worn or damaged spark plugs
  • The use of incorrect or unsuitable spark plugs
  • Excessive carbon or oil fouling of spark plugs
  • The use of substandard aftermarket ignition coils
  • Defective or corrupted ignition drivers in the PCM but take note that this condition is far more likely to set trouble codes that relate to low-voltage primary ignition circuit failures

What are the symptoms of code P2302?

Common symptoms of code P2302 are largely similar across all applications and could include one or more of the following-

  • Stored trouble code and an illuminated warning light
  • One or more misfire-related trouble codes may be present along with P2302
  • The engine may run roughly at all engine speeds
  • The engine may exhibit severe misfires that may or may not be intermittent, depending on the nature of the problem
  • The idling may be rough, or the engine may not idle at all
  • The engine may be hard to start
  • Fuel consumption may increase dramatically
  • Acceleration may be poor, and/or the engine may exhibit varying degrees of power loss
  • On older vehicles on which the PCM does not disable the fuel injectors on misfiring cylinders, catalytic converter failures may occur

Spark plugs on affected cylinders may foul repeatedly

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