inthechateau

96 Tahoe popped three DTC codes DTCP0131, P0138, P0151 then then went into a limp mode. All codes P0131, P0138, and p0151 are all O2 sensors. been having a p0138 for a couple weeks now and replaced the sensor. Was pulling hard on interstate when engine made a surge then lost all power. It never shut down but only made enough power to do 10mph to get off of road. Puled the codes and on start up engine ran with full power restored until full power was required to get up to speed. It then went into limp mode again and same three DTC reocurred. Any ideas?

Fuel gage went haywire a month agobut has not affected anything else so far.

Would weak fuel pump make it go like this. Wondering if weak pump would cause lean situation and cause Hi voltage on O2 sensors.

shamrock246

Did you check to see if any of the fuses are blown (eng-1,ecm-1) maybe an O2 sensor shorted out

inthechateau

Thanks for the hint, will definatley check that. Will run meter on fuses too but after i restart engine all seems well untill that required power demand is started. I was getting 21MPG out of this thing on a trip to Missori and back from Maryland. Love my Hoe and jsut want it to run liek that again.

inthechateau

No fuses blown, all are at power on proper function. Let truck sit for a few days after trip and rove it to work this morning. Ran fine but still setting O2 sensor DTC's. With no other sugestions I am going for fuel filter and fuel pump, fuel gage went any how.

the question is: Will a lean mix cause O2's to send signal high voltage on sensor one and lean on sensor 2? I am now thinking it is not the O2 sensors going bad but the mixture itself is actually going lean. Not sure of the signals for mixture paterns.

shamrock246

it could be fuel pressure,check for vacuum leaks and maybe clean the mass air flow sensor