Hello, I'm a new 2004 Is300 owner. I got it knowing it needs work I'm just trying to get 'er up and running for now(Which she doesn't). For starters it's been having induction issues, cover the air filter with your hand and it idles better. Leave it alone and it starts to bog down, I ended up replacing the air filter with a cheap Amazon one(I plan on making a custom intake later on).
When I got the car it ran and drove. I had to jump the battery in order to start the car but I replaced it with a better suited battery and now it's starting up fine. The issue now is it starts up idles for a little, bogs down, and dies. In the rare case it continues to idle (which only happened a hand full of times) apply any throttle and it dies. Me and my father can't figure it out why. The only thing that remains the same are the wires that go from the ECU to the connector but we've tested the wires with a multimeter and everything checked out. Tested the connector to the Actuator and that checked out. I'm kind of at a loss here. I've read that the throttle bodies tend to go bad. I've been through three different throttle bodies with the different actuators and still the same issue (keep in mind these were used). I have a hand full of codes, 1 engine code being the P2112 code, and three AC codes being the B1421, B1432, B1442. I feel the need to include the AC codes incase someone more knowledgeable can say whether or not they can effect the car as well.
I've got a couple ideas but wanted to get some help from more experienced 'Is' owners before committing to something. The list of ideas are, replacing the Actuator with a new one, replacing the air filter, I've also seen some folk get rid of the Actuator all together, and last idea being take another connector for the Actuator and run that wire straight the Ecu, just to test it. Maybe there's a break in the wire that's causing it to work sometimes and sometimes not. Any help works appreciate it!

 

From what you’re describing with the P2112 code and the car not starting, it really sounds like the ECU is getting confused by the temperature readings and shutting things down for safety. Checking the coolant temp sensor and the wiring around it is a good first step, since a bad sensor or bad connection can throw that code even if the rest of the engine is fine. Before ordering parts, it might help to test the sensor’s resistance and see if the readings make sense compared to actual engine temperature.