Hi guys, Im new to the forum, I was doing some searches on my problem with my IS300 and this site seemed to be the most knowledgeable, so I turn my problems to someone smarter. My car is throwing a cel and the trac off light is flashing and is limp mode. I had the codes read and it said multiple misfire(all cylinders) and o2 heater circuit bank 1. Not sure which bank was bank one, I replaced all the o2 sensors with Bosch universal sensors as they were the cheapest. I also changed the plugs and all three coils. the coils were after market, and the plugs were ngk. While changing the plugs I noticed there was oil in the valley, so i also changed the valve cover gaskets. After all of this, I plugged up the battery and went around the block. Everything was fine until it got up to temp, then the cel light came on again and the trac off light started flashing. The car went in to limp mode and now I am stuck scratching my head wanting to scrap the thing! any help would be appreciated. I havent made it back to the parts store to check the codes again.

 

I had an ECU causing that O2 heater circuit problem. The shop used an oscope to verify the heater circuit and the signal looked fine. Turned out to be that ECU causing that CEL. I'm not saying that your ECU is bad, but it may be worth a shot to take a look at that heater circuit bank. Welcome to clublexus and gl on the repairs

 

Thanks for the welcome. Well I limped it up to the parts store and they checked the codes. the o2 code was gone as well as the misfire. but it had a p1128, etcs trottle motor failure/throttle body assembly damaged or stuck, or ecm failure. it seemed to run better, but was idleing rough and had bad throttle reponse. would that be the IAC valve and motor?

 

my throttle accelerator position sensor went bad, same problem changed my tps no change on it. the accelerator sensor is the component that the throttle cable is attached to btw

 

ive also seen a bad maf cause similar problems

 

Would it throw the p1128 though?