98 ls400 fault code

robob · March 14, 2018

Hi, i have an ls400 1998, just clicked over 150k. Has niggles as to be expected as nearly 20 years old but always runs great.

This morning started up put in reverse and the car heavily jolted into gear and then check engine and check vsc lights came on. Accelerator pedal did not rev engine until the kickdown switch was depressed.

Turned it on and off several times and still the same, disconnected Battery for few minutes then tried again. Still the same.

Tried yet again but this time revved it hard the second it started. Now runs fine!!

Popped to a friends garage locally who knows nothing about these unfortunately but did manage to scan it and get code p0120 throttle position sensor.

Anyone had similar problems? Exhaust does have a tint blow up front somewhere but i don't think that is relevant? Always has oil changed every 6000 or so, clean air filter.

I haven't checked plugs as the service history showed it had new iridium plugs fitted about 5000 miles before if bought it and i have done about 15000 in it. That said i guess i ought to pull one out and take a look.

I did have a similar thing occur twice in a couple of days about two years ago, check vsc came on and no accelerator but that cleared itself after a restart and has never happened again until now.

Any input gratefully received.

Thanks

runsgrateasanut · March 14, 2018

Here's a thought. You can buy a new Sensor or there is a Lexus LS400 Throttle body on the Bay which has been cleaned and has a sensor for about the same money. A quick swap with new Gasket and you may have fixed two jobs - cleaning (which after 110k miles is I can confirm necessary) and Sensor to see if fixes problem.