TheGreenHulk

Hi, Working on a family member's Silverado 4.8. We have an SES light on and Reduced Engine Power on the Message Center. We replaced the TPS sensor given the codes we received, but this did not fix it after the OBDII reset. The codes are still: P1120 P1220 P1514 P1516 Whenever we reset the OBDII codes, the truck runs like nothing is wrong. After turning it off, and restarting after 5 minutes, the SES light, reduced power, and all codes return. Not sure what else I should troubleshoot next, but I assume maybe the throttle body is failing? We did real time analysis of the sensors to confirm the TPS, O2 and Pedal sensors are working. I don't have voltage specs but I can see everything appears to be normal. Looking to the forum for some recommendations from the bright minds here. This is my first post. Thanks for reading.