Michael88

Is there an intake air temperature sensor or is it built into the MAF sensor on this year? I did a live scan with the car running and the IAT is reading 125 degrees in 70 degree weather. Please, let me know if I am buying an IAT sensor or a MAF with the IAT built into it. Thanks. I believe I will be buying a MAF sensor with the IAT built into it.

Scraape

Intake air temp could easily get up to that if the car has been running , especially with hood closed and car idling .

But if it's reading 125 degrees when the engine is completely cold then you're right to replace the MAF sensor. IAT is built into it

dicer

So what scanner did you end up with?

Yamae

The intake air temperature is measured together with the amount of air by the MAF. So the MAF sends two different signals THA (air temp.) and F2G (air amount) to the ECU as is shown below.

Michael88

I replaced the MAF sensor due to an IAT code. I also replaced the driver's side upstream O2 sensor due to a bank 1 S1 code. So far, this LS400 has started 40+ times without a single intermittent no start. The only code that I did not address was a PPS/TPS sensor code, with the logic that these other sensors might have been "pushing the throttle" beyond its acceptable limits. I erased the codes and reset the computer, of course. No codes so far. Other electrical funny business like delays in the telescoping steering wheel have gone away. I speculate the O2 sensor had a short in it. I must share this. I ignored the O2 sensor code when it first appeared knowing it was something that could slide until I could do it. Thinking back, I bet I ignored this for nearly ten years and didn't see much of a decrease in mpg. Guys don't make the same mistake I did, and tell yourself the O2 sensor can be ignored then file that problem away. I am still considering ECU capacitors, but if I no longer have problems then I can have time to practice my soldering skills first.

spuds

DVL5WRK95 just had his ecu done for 90 dollars by Driftmotion in Montclair Calif and is happy with the work.