Error Code P1320 is defined as Ignition Signal, or Ignition Coil and Power Transistor. This code is set when the ignition signal in the primary circuit is not sent to the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) during engine cranking or running.

This error code is a manufacturer-specific trouble code, meaning it does not apply to all vehicles makes. Rather, it applies only to specific vehicle makes, such as Nissan. Specification on the definition, troubleshooting, and repairs still vary from one make and model to another.

Definition

The power transistor receives a signal from the ignition signal of the PCM. The ignition coil primary circuit is turned on and off by the power transistor. This on-off operation induces the proper high voltage in the coil secondary circuit. The malfunction is detected when the ignition signal in the primary circuit is not sent to the PCM during engine cranking or running.

Error code P1320 means there is a problem with the ignition coil or the wire to the ignition coil.

Common Symptoms

As with other trouble code, this error code activates the Check Engine light and registers the code.

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Possible Causes

The most common cause of this problem is the ignition coil; one or more ignition coils may have failed. Even if the coils are working, if the resistance of one or more coil is smaller or greater than what the PCM expects. Measuring the resistance of the coil outside the vehicle may not show failures. The common cause of coil failure is usually heavy conditions (hard acceleration) or certain temperatures.

There are many possible causes for this error code, such as:

  • Defective power transistor unit built into ignition coil
  • Open or shorted ignition primary circuit (circuit to signal coils)
  • Poor electrical connection in ignition primary circuit (circuit to signal coils)
  • Defective ignition system condenser
  • Fault in the crankshaft position sensor circuit

How to Check

Since the problem is in the ignition coil, you need to test each ignition coil of your vehicle. If your car has eight ignition coils, then you have to check all eight. Disconnect the coil to see the plastic harness connector that goes into the coil. Remove it by pressing the tab on top. Locate the ignition condenser going to the condenser by pressing the tab.

Verify that the harness connector is getting power. Use a basic multimeter, set it at Volts DC setting. What you want to see is 12V of power coming from the battery getting into the harness. The red wire of the multimeter should touch the first terminal, while the black wire (negative) is for the ground. Turn the ignition key to the on position, don’t crank it. If you don’t get 12V, then that means you have a problem in the harness connector. There must be splices at the back or chafing of wires.

Next, verify that ignition condenser is getting enough power. Again, test terminal 1. You should have 12V of battery power. If it’s not getting enough power, that means you have a problem in the wiring of the ignition condenser.

Again, conduct these tests in every single coil. For testing rear coils for older vehicles, you need to remove some parts that are on top of the ignition coils.

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Next is to check the coils themselves. Disconnect their harness connector. To test the resistance of the coil, you don’t need a key. There will be three prongs in the coils. The prong on the left is the prong no. 3, you should leave that alone and test prongs no. 2 (middle prong) and no. 1 (right prong). Use the multi-meter (set it at ohms setting), hook up one lead to no. 2, while the other is on the no. 1. What you should see is a reading. If you get 0 resistance that means the ohm is bad. Anything above 0 is good. Again, check all coils.

The last step is to test the resistance in the ignition condenser itself. You need to get a reading of over 1 mega ohm (M sig symbol on your multi-meter). If you don’t have that setting on your multimeter, then set your multimeter to the 1000 option. That means you just have to multiply any reading you get by 1000. 1 million ohms is equal to 1 megaohm. For this kind of multimeter, your reading must be 1000 or over. If it is under 1000, then you have to change the ignition condenser.

How to Fix

This error code is moderately easy to repair. Some of the most common repairs are:

Replace the defective coils

Replace faulty ignition condenser

Some people think replacing the coils can fix this problem. Don’t try to do that, as many times, the coil can be perfectly fine, and the problem lies in power getting to the coil. Thus, it is important to test it thoroughly.

Some models that don’t come with individual ignition coils, the ignition coil is inside the distributor, and the distributor needs to be replaced to fix the problem.