scrim67

I have a '98 gs 300 with 145k miles. My fuel light used to come on at around 325-350 miles. Lately it comes on at around the 300 mile mark.

The car has always run great but lately I've noticed a slight reduction in mpg.

I have never replaced the oxygen sensors and I surmise perhaps I should.

The check engine light is not illuminated.

Would any experts advise replacing the sensors at this point as a preventive maintenance?

If I do replace the sensors what's the least expensive way to get this done short of me doing the work myself. Can I buy these parts online? If so, where?

Thanks in advance for your feedback.

xravexboix

If the o2 sensors are bad, the check engine light will come on.

Have you been carrying any extra loads in the car lately? They said (approx) for every 200 LBS extra you carry, you lose 1 MPG.

Have you changed your driving habits? (ie Accelerating harder, more stop/go driving, less highway/freeway driving)

Have you checked your tire pressure? (should be done monthly) Low pressure helps your engine consume fuel!

The (most expensive lol) thing you can do is take it to a dealer and have them run a monitor test (accurate real time MPG readings on the tester)... takes 20 mins to do... will charge you an hour (or more =x )... We see these all the time (usually within Warranty w/ LX/GX, so they don't get charged...) and the test shows the MPG to be as stated on the window sticker...

Good luck!

scrim67

I have already run an STP product thru the gas tank that cleans the fuel injectors allegedly.

Coincidence or not, my MPG did improve by about 5-10%.

Also, I am going to replace the air filter which might help too.

About the 200 lb load, (there's a joke in there somewhere, but I'll refrain) I will also clean out my trunk as I'm sure there is stuff I can throw away.

Thanks,

scrim

TLW

when was the last time you got as tune-up ?

whitels

Check the wheel alignments, too. O2 sensor can be half-bad and the engine light will not come on. It happened on my GS400. During that time, the MPG went down drastically and acceleration suffered.

Lexicon1

Plugs, cap rotor, air cleaner, perhaps a fuel filter (not likely, but wont hurt at 145k miles), keep tires at correct pressure.(makes a difference)
Replace the O2 sensor, a likely candidate.
Read your plugs when you change them
Keep us posted

whitels

GS has no cap rotor. It has direct ignition system.