advsystems

My 99 GS4 is coming up on 60k miles & I was wondering if replacing the O2 sensor would be a good idea?

Thanks.

saber

Monitor your gas mileage. When mileage dips despite regular preventive maintenance like spark plug and plug wire replacement then it's time to consider replacing the oxygen sensors. Generally this is somewhere between 100-200,000 miles. Highway drivers get longer sensor life.

VVT-i

If it don't break, don't fix it. Your GS400 got 2 main sensors and 2 sub sensors and each of them cost around $200.00 X 4 plus labor, so you are looking to spend around $1,000.00 for nothing.

advsystems

Thanks for the advice - MPG is steady, so I will definitely wait on this.

saber

Only the oxygen sensor in front of each catalytic converter needs to be replaced when gas mileage dips because the front sensors wear out sooner. Replacing the sensors is easy if their two attaching bolts are not badly corroded. While the cost of two front sensors might be $325 from an online discount dealer, the 1-2 MPG improvement in gasoline consumption will offset this cost after about 20,000 miles of driving so it pays to change the sensors before they are completely shot and the check engine light comes on.

enterconne

Can you explain where the sensors are located?? My car is reading a 161 code.

meZoom!

I second this. If you *want* to kill your o2 sensors, run leaded gas and drive your car for a few short moments.

Lexmex

One batch of leaded gas will not kill your O2 sensors. A lot of guys at my track run SRT-4s with 115 Octane Sunoco leaded (with advanced timing) and they still pass emissions. No dead cat or O2 sensors.

meZoom!

It really depends on the car. On certain subarus and nissans (that i have tried at least), you run a few gallons of leaded 110 mixed with your california pump gas (91) and your 02 sensors will start to turn white. it depends on the car, but most will still not throw a check engine light at this point. The SRT4's are weird to me. I swore they didn't have standard catalytics...???

Lexmex

That's a good point that not all cars are affected the same. For instance, in Mexico catalytic converters were not a requirement until 1991 unlike about 1976 for the states. Even then, NOVA (leaded gas) continued until about 1999-2000. I asked a guy who worked at the emissions testing place here in my municipality since it opened in 1989 and he does not remember any cars having any O2 sensor issues (you need to have no check engine lights and must pass tailpipe).

More so, using leaded racing gas hardly does a thing unless you advance the timing. I see a lot of kids load it up at the track (just like they pour in octane boosters) and if they are lucky they get .1 difference in the 1/4 mile without playing with the timing. And the gas ain't cheap either.

One of my buddies races an RX-7 and with his engine management system he can adjust for the octane and fire spits out his exhaust (he ditched his cat since American-plated vehicles are not tested). He needs better plugs for sure, but it will make .4 difference in his time max.