Hi all,

While driving home today the SES light came on, and after searching how to pull codes Pulling codes I see that I codes 28 and 45. (Trouble code list)

28 is "3rd gear switch was closed or grounded for 10 seconds when vehicle was in 4th gear, or 3rd or 4th gear switch was open when engine was first started."

and 45 is "Oxygen sensor voltage was over 0.750 volts for 2 minutes in closed loop operation with a throttle angle between 0.6 and 1.9 volts."

Can anyone help me out with what these codes mean exactly and what I need to do to fix it?

Thanks!

 

have you ever had these codes before? did the light stay on or go back off the next time you drove the truck? it might be an intermittant or "false" codes. clear them and see if the light comes back on. you did not give any truck info (year,miles,engine etc...) this info would be helpful.

 

Ah, true sorry about that. Its a 1994 gmc jimmy sle 4x4 with 196k miles and W engine. Or CPI. Today we took it out and upon starting the SES light did not turn on. But after 40 or so miles on the way home it came back on. Also, while shoveling the driveway the exhaust seemed to burning really rich.

 

After getting the codes read and cleared at Brakes Plus a few weeks ago they just came back on today. Also 2nd tank of gas yielded 8.3 MPG.

Gonna do some research and see about this horrible MPG.

 

You need to do a fuel pressure test. 8.5mpg is gonna mean you have a leak. And the nut kits are a very common failure.