P0354 Malfunction of a primary / secondary circuit of the ignition coil D
OBD2 Error Codes

P0354 Malfunction of a primary / secondary circuit of the ignition coil D

OBD-II Trouble Code - P0354 - Data Sheet

P0354 - Malfunction of the primary / secondary circuit of the ignition coil D

What does trouble code P0354 mean?

This Diagnostic Trouble Code (DTC) is a generic transmission code, which means it applies to OBD-II equipped vehicles. Although general, specific repair steps may differ depending on the brand / model.

The COP (coil on plug) ignition system is what is used in most modern engines. Each cylinder has an individual coil which is controlled by the PCM (Powertrain Control Module).

This eliminates the need for spark plug wires by placing the coil directly above the spark plug. Each coil has two wires. One is battery power, usually from a power distribution center. The other wire is the coil driver circuitry from the PCM. The PCM grounds/disconnects this circuit to activate or deactivate the coil. The coil driver circuit is monitored by the PCM for faults.

If an open or short circuit is detected in the excitation circuit of coil # 4, a P0354 code may occur. In addition, depending on the vehicle, the PCM may also disable the fuel injector going to the cylinder.


Unlike some other codes, when a code P0354 is stored, you will almost always notice more symptoms than the Check Engine light is on. In addition to this (or MIL coverage), common symptoms include:

  • Engine misfiring (may be permanent or intermittent).
  • Rough idle engine
  • Acceleration skips
  • MIL Illumination (Malfunction Indicator Lamp)
  • Engine misfires may be present or intermittent

In some rare cases, you may not notice any symptoms other than the Check Engine light coming on.

Causes of the P0354 code

Several issues can cause a vehicle's powertrain control module (PCM) to store a P0354 code. Some of the more common causes include:

  • Vacuum manifold leak
  • Faulty ignition coil(s)
  • Faulty idle control valve
  • Faulty electronic housing
  • One or more faulty spark plugs
  • Short to voltage or ground in the COP driver circuit
  • Open in COP driver circuit
  • Bad connection on coil or broken connector locks
  • Bad coil (COP)
  • Defective transmission control module

Possible solutions

Is the engine experiencing a malfunction now? Otherwise, the problem is most likely temporary. Try wiggling and checking the wiring on spool # 4 and along the wire harness to the PCM. If tampering with the wiring causes misfires on the surface, fix the wiring problem. Check for poor connections at the coil connector. Make sure the harness is not knocked out of place or chafing. Repair if necessary

If the engine is currently malfunctioning, stop the engine and disconnect the No. 4 coil harness connector. Then start the engine and check for a control signal on coil # 4. Using the scope will give you a visual reference to observe, but since most people don't have access to it, there is an easier way. Use a voltmeter on the AC hertz scale and see if there is a reading in the range of 5 to 20 Hz or so, indicating that the driver is working. If there is a Hertz signal, replace the # 4 ignition coil. This is most likely bad. If you do not detect any frequency signal from the PCM on the ignition coil driver circuit indicating that the PCM is grounding / disconnecting the circuit (or there is no visible pattern on the scope if you have one), leave the coil disconnected and check the DC voltage on the circuit driver on the ignition coil connector. If there is any significant voltage on this wire, then there is a short to voltage somewhere. Find the short circuit and repair it.

If there is no voltage in the driver circuit, turn off the ignition. Disconnect the PCM connector and check the integrity of the driver between the PCM and the coil. If there is no continuity, repair the open circuit or short to ground. If open, check the resistance between ground and the ignition coil connector. There must be endless resistance. If not, repair the short to ground in the coil driver circuit.

NOTE. If the signal wire of the ignition coil driver is not open or shorted to voltage or ground and there is no trigger signal to the coil, then a faulty PCM coil driver is suspected. Also be aware that if the PCM driver is defective, there might be a wiring issue that caused the PCM to fail. It is recommended that you perform the above check after replacing the PCM to ensure that it does not fail again. If you find that the engine is not skipping ignition, the coil is firing correctly, but the P0354 is reset continuously, there is a possibility that the PCM coil monitoring system may be malfunctioning.

Common Mistakes When Diagnosing Code P0354

One of the most common mistakes in diagnosing the cause of a code P0354 is diagnosing a faulty ignition coil when the actual cause of the problem was a vacuum leak. Similarly, some people suggest that spark plugs need to be replaced when the problem is due to a vacuum leak or some other cause.

How serious is the P0354 code?

In most cases, when a P0354 code is stored, the vehicle will run rough and either intermittently or constantly misfire when accelerating. These symptoms can be unpleasant at best and dangerous at worst. Think about what can happen if you need to accelerate quickly, but your car misfires and does not behave as it should.

What repairs can fix code P0354?

Some of the more common repairs for a P0354 code include:

  • Replacing or repairing a leaking vacuum manifold
  • Replacing faulty wiring ignition coil(s)
  • Replacing old or non-compliant spark plugs
  • Replacing or repairing the ignition coil(s)

Additional comments to consider regarding code P0354

In addition to making driving unpleasant and potentially unsafe, a stored P0354 code can make it difficult to renew your vehicle's registration. To pass the OBD-II emissions test, you cannot have the Check Engine light or MIL light on, and one of those lights will stay on until you fix the problem and clear the code.

How to Fix P0354 Engine Code in 2 Minutes [1 DIY Method / Only $3.85]

Need more help with your p0354 code?

If you still need help with DTC P0354, post a question in the comments below this article.

NOTE. This information is provided for informational purposes only. It is not intended to be used as repair advice and we are not responsible for any action you take on any vehicle. All information on this site is protected by copyright.

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