I have a P0401 code up solid. I have changed the EGR valve and modulator. I suspect the EGR temperature sensor is bad, but I do not want to spend $175 to find out. Can I measure the detector with a Meter to see if it is bad? What should I expect to see if it is still working? "
How can you test an EGR temperature sensor to see if it's bad? on 1996 Lexus LX450
by weir9cuv in Mahwah, NJ on September 12, 2010
ANSWER by dandd on September 12, 2010
Before you TRY anymore parts, really you need to find the problem. It could very well be a plugged up system, and not need ANY parts. here is an article I wrote on P0401 Diagnosis for any Toyota, which includes Lexus. http://repairpal.com/OBD-II-Code-P0401-Toyota
ANSWER by yota tech on March 09, 2012
you'll need to have a scan tool to see engine data. with key on engine off egr temp should be 50 degrees F or more. Now check to see if there is aproblem in the harness. Disconnect the EGR temp sensor connector and jump the terminals together with key on engine off. Temp should read 318.7 F. Then you'll need to run the engine at 4000 rpm for 3 minutes and check egr temp again. should be 212 degrees F. or more. If any of these values are off significantly the sensor is bad. They are available aftermarket for 120.00 to 140.00