Yogi Bear

Trying to figure out positive and negative LTFTs here. If the LTFT #s are positive, does that mean that the motor is lean and the PCM is having to add additional fuel?

Could an old O2 sensor (190,000 miles) cause this? Could the old O2s also cause a P0174 (lean bank #2) DTC?

'96 Chevy Blazer, 4.3L "W" motor.

Atomic

iTrader: (42)

Yes. positive means its adding fuel, negative is cutting fuel.

possibly, may as well replace them anyway, they are pretty old.

FrostKing

I would also replace them. Normally o2 sensors fail making the engine on the rich side.

Yogi Bear

OK. Thanks for the replies!

wait4me

iTrader: (10)

WOW you got alot of miles out of that sensor. I believe i read in the tech docs for the sensors being used and they start to degrade after 30,000 of "NORMAL" use. When and if they die obviously depends on driving habits and quality of gas being used. I try to replace all mine at 40,000 miles just to be safe. The slower they get the more they hang on the rich or lean side while switching.