Toyota misfire codes — What are the causes

Toyota Misfire codes P1300, P1305, P1310, and P1315 — The Most Common Causes

Common Toyota misfire codes. In addition to P0301, P0302, P0303, and P0304, you may also see P1300, P1305, P1310, and P1315. The P1300, P1305, P1310, and P1315 codes are manufacturer specific codes and they tell you that there’s a problem in the ignition coil igniter circuit.

Most common causes of  Toyota Misfire Codes P1300, P1305, P1310, and P1315

These codes are telling us that the ECM has detected a problem with the ignition coil IGNITER circuit. A full description of the igniter circuit is shown below. In short, there’s a problem with power to the power transistor inside the ignition coils, a ground problem to the igniter circuit, or a failure with the transistor that switches power to the primary circuit.

In Toyotas, the most common causes of P1300, P1305, P1310, and P1315 trouble codes are a poor or missing ground or a problem on the power supply side.

Start your diagnosis by checking for battery voltage at each ignition coil terminal #1 with the key in the RUN position. If the coils are getting battery voltage, check the ground connection from the ignition coil wiring harness on the engine. Remove and clean the ground, clear the trouble codes and see if they stay off.

If that doesn’t solve the problem, check for a digital signal to the the switching transistor in the problem coil. If you’re not seeing a digital signal, check the condition of the crankshaft position sensor. Use a scan tool to check for live data from the CKP sensor.

How the Toyota Ignition coil igniter works

What is an igniter? In simple terms, it’s the switch that turns power on and off to the ignition coil primary circuit.

When turned on power flows to the primary circuit of the ignition coil to build a strong magnetic field. When power is turned off, the magnetic field collapses, producing upwards of firing voltage of around 40,000 volts to the spark plug. This is called the secondary circuit.

Modern Toyota ignition coils use a transistor inside the head of the coil to switch the power on and off to the primary circuit. The transistor receives a digital on/off signal from the ECM telling the transistor when to turn the power on and off.

How does the ECM know when to notify the transistor? It uses signals from the crankshaft position sensor.

What is Toyota IGT verus IGF

IGT is the “trigger” that tells the transistor when to turn power on and off to the primary circuit

IGF is a return signal to the ECM informing the ECM that the coil did indeed fire. The ECM uses the IGF signal to detect misfires and to calculate RPM.

How Toyota ignition coils are wired

Power is supplied to Toyota ignition coils from the ignition switch. Power flows from the battery to the ignition switch and then to a junction box, and from there to each coil. Battery voltage powers the transistor and is the power to energize the primary circuit.

Each coil has a ground for the transistor and the primary coil. The ignition coil ground usually terminates on the engine.

©, 2022 Rick Muscoplat