Check Engine Light

[JSTANCOFF]

99 ES 300 check engine and trac off lights on. My mechanic said the code read PO 171 lean cond. but he wasn't sure exactly what that meant. Any ideas?? I really don't want to pay the stinking $89.95 to take it to Fresno Lexus. Appreciate any feedback.

[SKperformance]

possibiities are egr valve staying open

but that has a seperate sesnor code

also was only a problem with the first gen 1mz-fe engine

your maf may be reading wrong

or there might be a hole in the intake pipe causing it to suck more ari in after the air filter and maf sensor

low fuel pressure but that is unlikley also

jpi might have a good idea

[Toyota/Lexus Tech]

How many mile are on your Lexus, I work at a toyota dealership, I've seen this code on Corollas, 4runners, and the v6 Tundra, and they were all caused by the MAF, I always check the range with the scanner and find that it's off at 2500 rpm, and it's in range at idle. I will also see the LTFT jump to -38 while accelerating even moderately. Our parts delivery Tundra had that problem and it got extremely good gas mileage, but I imagine the NOx emissions must skyrocket. The part is quite expensive though, but it's easy to install, maybe have it diagnosed and replace it yourself

[SKperformance]

if it might be a maf problem check you hose to see if it has a crack which can also cause a problem

[gurubaba]

I have seen this same thing on my 99ES300 as well....surprisingly the check engine and trac off lights went"off" automatically after driving about 50miles or so....although one thing that bothers me is that I do not get good mileage....about 22mpg hwy....i have heard people getting up to 26mpg.