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.

 

You have an issue with your throttle position sensors and mass air-flow control.according to the OBD II codes.you posted.

 

Hi, we have replaced the TPS already just before the same codes appeared on the scanner.

 

Did you install a new MAP sensor?

 

Hi,

I can confirm based on realtime voltage checks that MAF and MAP aren't working. Also won't a Map error trigger a different DTC?

 

you did good. isolate the problem by trying to trace to what part you need to exclude from possible set.

(do them in a deterministic order, or just after the most obvious ones)

Test the components and if they fail replace them: since they are certainly bad if they failed the bench test.

(being electrical, make sure there is no bad voltage in the area. why did they fail? soaked in trans fluid? just old? cracked wires leading to them? bad signal due to poor wiring?)