I have a 2003 Chevy silverado and got an error code reading Bank 1 Sensor 1 Faulty. Replaced Upstream sensor and still getting same code. Checked all fuses they are fine truck sounds fine but gas mileage has fallen off any suggestions would be great!

 

My Haynes says heater performance left bank. If the connector is clean, and solid, try another sensor, or if possible swap the two left/right if the problem follows then it is the sensor, if not wiring. New parts dosen't always equal good parts.

 

yea heater circuit codes are almost always the sensor. What brand did you use? I would recommend OE

 

I plugged in Obd2 code reader & got these codes P0135 (02 sensor heater circuit malfunction bank 1sensor 1), P0171 & P0174 ( System too lean bank 1&2), P0300 Random/multiple Cylinder Misfire Detected. II don't have a clue where any of it is or how to replace them. Please help

 

I have an 05 Trailblazer that is running rough. ROMs going crazy. Acts like stuck in neutral. Can get it to go to 3rd gear. Then have to let off gas reduce speed and it shifts to next gear. Computer gave codes for 02 sensor fuse, cylinder 4 misfiring, low coolant temp and air register issue. Fuse looks good. Didn't know what to do for last 2 so changed cylinder 4 coil and plug. ( never been changed- I know I shoulda done all!!))
also plug had some oil on it. This fixed the issue for about 10-15 mins then it started again. Never got as bad as 1st time, could actually go 55 mph but still had RPM whining sound. If anybody has any suggestions, all are welcome and appreciated. !!

 

since you're having all those issues I would first check your intake manifold to see if there's any kind of cracks or openings anywhere there could be any excess air coming in if your intake manifold is good, if your vehicle is having issues and or problems going uphill or having any issues accelerating I would say it would be your fuel pump because you are having random misfires but before you check the fuel pump I would check the fuse itself and then I would expect that is the fuel pump that it's going bad but first I would go to AutoZone or O'Reilly to ask for a fuel pressure gauge and test your fuel pressure check your handbook or get information and how much pressure your vehicle is supposed to be pushing through the fuel lines

 

Stuck in 2nd gear.
I know this is a very old post but as I read it. I thought maybe I had already written in. This is exactly my problems.
Just wandering how your situation turned out or if anyone has any new solutions or input. Thanks in advance.