i had checked my lexus LS400 Model 2000 with a computer and i had got these error codes..
P0505 idle control system malfunction

B1421 solar sensor circuit (passenger side)
B1424 solar sensor circuit (driver side)

please help me with the meaning of these codes and how to fix these errors??

 

Don't worry about the solar sensor circuit. All Lexus cars have these codes, even the brand new LS600hl. Plus, you can't clear the codes. Just ignore it.

 

Yep, 100% normal.

 

Sorry, I didn't see the P505 Idle control circuit. Most of the time this code mean your throttle body goes bad and won't idle.

 

Wow, i completely missed that too. Nuum is right, usually its a bad throttle body. The little motor that controls the throttle blade goes bad sometimes. Unfortunately, a new throttle body is $1000+...

 

Solved the P0505 idle control system malfunction, it was also giving idle problem while AC is on and car on Parking gear (P). It was just all about cleaning the throttle body by cleaner.
http://images.google.ae/images?hl=ar...-8&sa=N&tab=wi
My TB was full with carbon LOL, but now its clean & clear. It is easy job.

 

Great tip! I didn't get a P0505 but did get tge B1421 & B1424 solar sensor codes. I will clean the Throttle Body and see if this solves the irratic idle speed. Thanks for the info.
LCAN

 

A fine is a tax for doing wrong. A tax is a fine for doing well

 

if you pull these codes in a darker area like inside a garage, that may throw them. clear the codes and do the check in the sunlight.