p1300 Ignition Simulator

Ok this is the biggest CEL all of us get when we go complete fuel & ignition standalone. For a cool $2 you can get a 2N3904 transistor and switching diodes to beat it.

If you live in a state that deals with OBD2 emission testing, you’ll need to do this to pass inspection. For the past 2 weeks, I’ve been reading as much as I can on the Toyota ignitor and the purpose of IGT and IGF. To save you guys all the trouble, this is all you need to know. IGT is the trigger to fire coil pack #1, IGT2 is the trigger to fire coil pack #2, and IGT3 is the trigger to fire coil pack #3. When the coil pack is fired, the IGT signal goes high (positive voltage) and a return IGF signal, low (ground), needs to go back to the ECU to confirm everything is dandy. Without the return signal, you’ll get the dreaded P1300 CEL.

So when IGT goes high IGF needs to go low!

Here’s what needs to be done to create the circuit:

  • 3 switching diodes
  • 1 NPN transistor

The diodes are basically 1 way valves, IGT goes to input of 1 diode. IGT2 goes to the input of another and IGT3 goes to the input of the 3rd. Connect the other end of the diodes together and this connects to the BASE of the transistor. The transistor has 2 other ends, a COLLECTOR and an EMITTER. The COLLECTOR connects to the IGF. The EMITTER connects to a ground source.


The 3 red wires are the IGTs, the green is the IGF, and the black is ground. Pull the negative battery terminal and solder the connections together and voila the P1300 CEL is defeated. The way this works is when a trigger is applied to the BASE, the EMITTER will send the ground signal to the IGF and simulate the ignitor.


I have these for sale in the store if you are interested in just purchasing one.