2005 Hyundai tucson hesitation and stalling issues

the mechanic that said I need a whole new cat said there’s no codes popping up when he plugs in his diagnostic reader. but years ago my check engine light came on took it to advanced auto and had them plug their diagnostic reader and a bad o2 sensor error code popped up. but the guy told me not to worry about it because the sensors last along time. lesson learned!

I know i’m really late to this thread but had to reply. I have a 2005 Hyundai Tuscon which is what brought me to this conversation. My car would stall out if I was driving 65 MPH or idling in my driveway. No service code! Random, sometimes had trouble restarting but usually restarted right away. My Crankshaft position sensor was bad, (harness to sensor wire coating were melted away exposing wires) that was the original service code. I replaced the Crankshaft Position Sensor. Thought all would be OK but stalling continued. Checked harnesses, seemed OK, looked for melted wires in fuse boxes, all OK. Luckily while idling in my driveway I noticed something new, the cabin blower motor turned on by itself for a few seconds maybe a minute then shut off. Seconds after that the car stalled which sent my attention to to blower motor. I found that the blower motor is attached to something called a Blower Motor Resistor. You don’t need any tools to get to this, it’s located under your glove box, just follow the wire from the blower, it will lead you to it. Disconnect it, very easy (look it up on youtube if your not sure). Solved all my problems, There is a heat sink in this circuit, obviously it produces a lot of heat, my guess over time you can get an arc across circuits that messes with pcm & kills engine. Hope this helps someone that finds this thread

Did you replace the blower resistor or just disconnect it @Dmckellar8_141488 ? The latter would probably result in a blower fan that only ran on hi speed. So you’d have either off or hi, nothing in between. It’s curious that a blower motor resistor fault could cause the engine to shut off. That resistor does get hot though, and I suppose that heat could adversely affect something else in the ignition or fuel injection system. Or cause inconsistent current loads, arcing, etc on the electrical system and confuse the ecm like you posit above. Good info to know in any event.

I didn’t replace it yet, I’m waiting on a new one. I’ll post how it went after it’s installed. Yes, it only runs on the highest speed.