O2 sensors???

[bigT5]

just out of curiosity is there a way to know when you need to replace O2 sensors???
also here where i live we dont have to pass emissions tests

just one other thing about catalytic converters i know they are illegal to remove. but i have heard two things, the first thing i heard was that they kill gas mileage. i have also heard that they help gas mileage greatly.... so which is it thanks

[MT-2500]

Originally Posted by bigT5

just out of curiosity is there a way to know when you need to replace O2 sensors???
also here where i live we dont have to pass emissions tests

just one other thing about catalytic converters i know they are illegal to remove. but i have heard two things, the first thing i heard was that they kill gas mileage. i have also heard that they help gas mileage greatly.... so which is it thanks

It is time to replce 02 sensors when the stop working right or giving the computer a bad reading.
If a 02 sensor or cat gets real bad it will usually but not always set a check engine light.
A engine capable scanner read out of 02 sensors and cat will tell you if they are working or not working right.

As far as to repace them.
When they stop working right is a very good time to repace.

If you keep you engine tuned up with the OEM type plugs and running right and other sensors woring right cats and 02 sensors sometimes will out last the vechical.
Remember there is many sensors that have to work together to get the job done right.

Some say replace 02 sensors at 100K or other mileage.
But with some trucks and cars with 4-5 02 sensors and 2-4 cats that can run up to 2 grand USA dollars.
I never replace them untill they get bad or weak.

As far as gas mileage.
Keep the engine tuned up right.
A bad cat or 02 sensor will kill gas mileage.
A bad tune up will kill cats and 02 sensors and gas mileage and if not fixed will kill engine.

Good cat and 02 sensrs will improve gas mileage.
The engine uses 02 sensors to adjust and set fuel mixture and tell the computer if cats are working right.
Most adjust the fuel mix at 14.7-1.

[j cAT]

Originally Posted by bigT5

just out of curiosity is there a way to know when you need to replace O2 sensors???
also here where i live we dont have to pass emissions tests

just one other thing about catalytic converters i know they are illegal to remove. but i have heard two things, the first thing i heard was that they kill gas mileage. i have also heard that they help gas mileage greatly.... so which is it thanks

the oxygen sensors are normally good for about 100-130.ooo miles.. sometimes depending on the vehicles care and operation they do last longer..when these get old they do not correctly work..this causes loss of mpg and power....this can cause cat converter damage over time..


the companies that make oxygen sensors say 100,ooo miles is the life ...that would be a save replacement interval ....


the cat converters made in this vehicle do not effect MPG if in good condition..if this componet is bad this will reduce power and MPG big !

with a oxygen sensor going bad or other component failures like dirty injectors, coolant being burned etc...these cat converters will rapidly fail..



If you have bad cat converters removal of them will cause the engine to run better... I remove the upstream O2 sensors and with the hole open drive vehicle to see if the power issues/poor engine running is corrected..for testing .............

[bigT5]

ok i was just wondering because when i got this truck it had numerous problems with it, it was a old work truck for a power company here so of course they really didnt care. and this truck in a way got hammered so not much other than what was necesary as for maintenence (oil change,things that would cause it not to run) was done for it. it has 204000 miles and i bet the O2 sensors have never been replaced so i might just replace them anyway

[bigT5]

o and all the company did with it was drive it around and check people's power meters pretty much

[MT-2500]

Originally Posted by bigT5

ok i was just wondering because when i got this truck it had numerous problems with it, it was a old work truck for a power company here so of course they really didnt care. and this truck in a way got hammered so not much other than what was necesary as for maintenence (oil change,things that would cause it not to run) was done for it. it has 204000 miles and i bet the O2 sensors have never been replaced so i might just replace them anyway

What year and truck and engine?
I would Start with the basics.
Ac delco tune up and check compression with tune up.
Any check engine lights or codes?

[bigT5]

its a 1996 chevy cheyenne with a 350 in it and iv already done a tune up replaced the alternator, replaced a radiator hose, replaced the back end, replaced the fuel pump and fuel filter, replaced the fuel pump relay, replaced a U joint, and thats all i can think of at the moment its a way better truck now then it was when i got it

[j cAT]

Originally Posted by bigT5

its a 1996 chevy cheyenne with a 350 in it and iv already done a tune up replaced the alternator, replaced a radiator hose, replaced the back end, replaced the fuel pump and fuel filter, replaced the fuel pump relay, replaced a U joint, and thats all i can think of at the moment its a way better truck now then it was when i got it

If you believe that the O2 sensors have 200,ooo mi on them replace the upstream sensors ...these are the important ones since these control fuel mixture...

the down stream sensors measure the exhaust gases to report to the computer how well the cat conveters are working...so these will not effect how the vehicle engine runs..


At 200,ooo mi your cat converter could have issues..