Not Shifting Onto O/d

[PaulS]

My 2000 ES300 will rarely shift into O/D. The engine light is on but I'm not sure if it is related to the transmission. The Lexus dealer checked the codes which indicated a spark-knock sensor had failed but they did know for sure if replacing the spark-knock sensor would fix the O/D problem. Has anyone out there experienced a problem with their O/D? Any tips would be appreciated.

Cheers,

Paul

[wwest]

My 2000 ES300 will rarely shift into O/D. The engine light is on but I'm not sure if it is related to the transmission. The Lexus dealer checked the codes which indicated a spark-knock sensor had failed but they did know for sure if replacing the spark-knock sensor would fix the O/D problem. Has anyone out there experienced a problem with their O/D? Any tips would be appreciated.

Cheers,

Paul

If there some reason, ANY reason, for the engine ECU to "think" the engine HP/Torque production is not up to snuff then it will not use O/D. In O/D the engine will oftentimes be operating right on the cusp of "lugging", knock/ping. Lowest engine frictional contribution, BEST FE, but only "just" barely producing the required HP given the "cruise" roadspeed.

[PaulS]

Replacing the Spark Knock sensor fixed the problem. I'm glad I took your advice instead of doing all the things the dealer wanted me to do. Thanks for your help :)

Cheers,

Paul