Ok I know one of you guys have access to this information. A friend of mine has a 1996 GMC Sierra 4x4 1/2ton 350ci motor.


He pulled the following codes


1406


1133


134


The million dollar question is does anyone know what these codes mean? He's got around 100k on it now and wants to get another 100 so he needs to know what needs tweaking.


Thanks in advance.

DTC P1406 EGR position sensor performance


DTC P1133 HO2S insufficient switching bank 1 sensor 1


DTC P0134 HO2S circuit insufficient activity bank 1 sensor 1


The EGR code could be affecting the O2 sensors. The EGR gets plugged with carbon and removing it and cleaning it usually fixes it.

GMCSID,


Nice to know there's another expert online with us.





Anyhow, thanks for the quick response.