Oxygen Sensors

[justinterested]

Hi Everyone... I have a 1995 LS400 with 123,000 miles. Car runs great but lately getting the smell of heavy gas from the exhaust at startup. My question: Is this a sign of Oxygen Sensors going bad?? Check engine light has not been on and the car is "code" free. Any help greatly appreciated.

[curiousB]

Probably just the car running open loop until it warms up. O2 sensors need to warm up before they can provide accurate signal to the ECU for trimming air fuel map accurately. In the warm up phase they send a deliberately rich mix rather than erring on too lean.

So if its only at startup then this isn't likely a concern.

[ggemigniani]

What does "smell of heavy gas" mean? Raw gas or visible black smoke out the tailpipe? Did the exhaust used to smell or look cleaner?

[ggemigniani]

What does "smell of heavy gas" mean? Raw gas or visible black smoke out the tailpipe? Did the exhaust used to smell or look cleaner?

[justinterested]

What does "smell of heavy gas" mean? Raw gas or visible black smoke out the tailpipe? Did the exhaust used to smell or look cleaner?

Tail pipes are clean - no buildup of any kind. No black smoke at any time. No gas leaks anywhere to be found. The smell of gas is only thru the exhaust and only duriing startup.

Thank you for your comments...