Hey guys! Sorry this is a little long, but I need help! My T/A is bone stock (LG4, 305 V8, Carb, and only has 80,000 original miles!) Been having some issues with trouble codes lately. So when I originally checked the codes a couple months ago, I noticed I was getting Code 13 (O2 sensor) and Code 42 (EST). I heard that having a bad 02 can also cause a Code 42, maybe I'm wrong. That's why I am here on Thirdgen. I noticed when driving before I got anything changed that my Check Engine would come on when the car was warm and the light only came on when I stopped, as soon as I started driving again it was gone. (I thought it was a soft code) Anyways, long story short, I replaced my old O2 with a new Bosh #12014 and got a new air filter. I noticed the car seemed to be smoother and have more power. Took off the battery cables and let the car sit overnight (to reset the ECM) The next day, took the car out for a spin, once the car has gotten warmed up BAM! Check engine! except now once the light is on, it stays on no matter what, unless I shut the car off. Checked the codes by the way before posting this and all I am getting now is Code 13. No more Code 42. Any help or suggestions would be great. Thanks!

 

Code 13 is an open in the oxygen sensor circuit. Since you already replaced oxygen sensor, carefully check the wiring from the oxygen sensor back to the harness, make sure no kinks, cuts, etc. If all is good in the wiring, then chances are your throttle position sensor is sticking. If Code 42 returns, replace your ignition module in the HEI.