Yesterday I had the thermostat replaced in my 2006 ES330 Lexus (141000 miles). Drove the car home from the mechanic and took one other short ride last night. Everything was fine. This morning I started up the car and noticed that the Malfunction Indicator light was activated. Per the owners manual I opened the gas cap re-screwed the gas cap. Light remained on. I then popped the hood and did an inspection of the thermostat repair hoping to see a vacumn hose out of place. Nothing found. Does anyone having any suggestions before I return the vehicle to the shop on Tuesday.

 

You need to get ahold of a code reader and read the error code in the ECU. This will tell you what the problem is that is causing the light to turn on.

Autozone will read the code for free for you.

 

go autozone!!wish that was the case in Canada too

 

Well, took your advice and contacted the nearest Autozone in Northern California. They do not offer code reading in this state. Figures.

 

The check engine light having come on after the thermostat was changed, could well be a coincidence, unless of course something did get disconnected by error.

Tightening the gas cap, (if that was the cause) does not cause the light to turn off imedialey. It may take a day or so.

You really do need to read the code, to be able to determine what the next step should.
Maybe the mechanic that changed your thermostat will check it for you for free.

Phil

 

autozone does lend you the code reader in CA. you need to do it yourself. very simple to do it.

 

Returned the lexus to the garage on Tuesday. Of course when the mechanic started the vehicle the malfunction indicator light was no longer illuminated. Did system checks and everything was OK. Apparently it takes a restart after driving approximately 100 miles to reset the indicator. Thanks for all the assistance on this.