Hi folks,

On my 2008 RX 400h with 195K miles -- both times right after heavy acceleration (100 kW+) and going uphill on the highway, I got a check engine light that seems innocuous.

I don't really notice any issues driving the car, and both times it clears up by itself after 3-4 trips.

I pulled up my handy Techstream to get detailed data on systems at the time when the light came out, attached below. I think the data is cool. What do y'all think could be the cause? Should I try to replace any components? Or leave it be since it's quite rare?

 

Lot of data there, but the LTFT is about maxed out. I would research to see if that relates to the MAF, or is a simple vacuum/manifold leak?

 

Start with routine maintenance. I'd suggest:
#1 - replace your vent lines (total cost likely under $20. I have 170K miles on mine my lines were badly cracked. Got mine at Autozone
#2 - remove the MAF spray it with some MAF clkeanrer (never use any other cleaner and never touch the element). Spray can be found at Walmart cheaply
#3 - While there wipe out the throttle body and inlet with brake cleaner

All that takes maybe an hour with very basic tools and limited mechanical knowledge

After cleaning MAF and Throttle boddy disconnect your battery for a couple mins then reconnect (yes you'll have to do a window, sunroof and tailgate reset) this resets your ECM. Your car will take maybe 50 miles to relearn your driving technique. After all that recheck your engine values on Techstream

 

How to Fix

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Possible Causes

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

• Dirty Air Filter
• Dirty Mass Air Flow (MAF) Sensor
• Intake air leaks
• Faulty Mass Air Flow Sensor
• Mass Air Flow Sensor harness is open or shorted
• Mass Air Flow Sensor circuit poor electrical connection

Before replacing the Mass Air Flow (MAF) Sensor, try replacing the air filter and cleaning the Mass Air Flow Sensor with low compress air or Mass Air Flow Sensor Cleaner. Reset code and drive vehicle. If the code comes back, you must replace the Mass Air Flow Sensor to fix the problem.