Three warning lights on the dash.
Code reader shows P0171, P1170 and C0300
Replaced fuel cap, replaced battery, did not help.
Next planning to clean MAF sensor
what might be the cause? Thanks in advance for your help.

 

searched and found a similar case, the solution was:
Smoke testing done by "local" GM dealer found the culprit. The Emission Evaporative Purge Solenoid Valve was replaced AND the 6" long rubber hose attached to the valve was hardened and allowing a small amount of leakage. Mechanic indicated the probable cause was the hose and the Purge valve may have been ok. I elected to leave the new valve in place and keep the original as spare or souvenir. Total cost: $196...

https://www.clublexus.com/forums/ls-...-gas-tank.html

 

another case: "
Sometime the EVAP line pipe may crack over the time and turn the check engine on. Lexus LS460 when the emission system issues then the check engine on and the VSC automatically also come on.
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PVC valve located under the intake manifold fixed my issue and I had the same symptoms as you did.
Only code with tech stream was the O2 sensor code I think P0170.
The sensor tested in spec.
I needed valve covers done on both sides when it started acting up.
The PVC valve gets stuck open or stuck closed and the causes the rough idle and the check engine VSC light on the dash.
It can also trigger the abs and VSC light on the dash at the same time.
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My 08 LS460 had this as well and it was the accumulator for the ABS system. $2K later no more codes. If your brake fluid has never been flushed try that first.

https://www.clublexus.com/forums/ls-...dashboard.html

 

Been there paid a bit more a few years back.

 

more cases:
I went through all of the recommendations I could find to address the VSC PCS light issue.
- Changed the battery- Only fixed it temporarily with the reset
- Replaced old gas cap- Again temporary fix if any but still good replacement to have
-Cleaned the MAF Sensor- BINGO!!! A simple can of MAF Cleaner solved this issue completely.

I have now driven for over 5000 miles including a trip to Vegas in 120 degree heat and the Lexus is running strong!

The answer to this frustratingly nagging issue is cleaning the Mass Airflow Sensors!!!

https://www.clublexus.com/forums/ls-...ight-on-2.html

 

one more case: FYI, I used to get P1170 codes randomly (like once per month). When I fixed my valley plate leak I noted it had been leaking for quite some time and I had some build up around some direct injectors with dried coolant. Not sure the relation, but ever since fixing my valley plate more than 9 months ago, I have not gotten a P1170 code or any CEL’s for that matter. If you haven’t fixed your valley plate, take a look and see if you are due.
https://www.clublexus.com/forums/is-...rame-data.html

 

Ok....MAF
What the hell does any of that have to do with Vehicle Stability Control? What genius programmed the computer to trip the VSC light to come on for everything plus Stability issues?

 

Toyota. They are idiocy personified, you have a EVAP leak and they take your VSC.

Contrast this to German cars that ONLY take it if there is an error in the actual VSC system, zero regard is given to even a dead missfire as that doesn't stop the ABS from firing or adaptive steering from altering angle.

 

Got checked by a very reputable mobile mechanic.
Smoke test and visual inspection, no air leak
Scanner showed no misfire, plus spark plugs were replaced 30k mile ago.
MAF sensor checked out fine,
only thing left are fuel injectors/fuel pumps.
Suggestion was to run fuel injector cleaners and go from there.

 

Check your battery too. Electrical issues caused by failing batteries can cause these lights to come on.

 

yes forgot to mention that
I replaced the battery 2 months ago (old battery was a 2.5 year old costco kirkland battery)
also replaced gas tank cap about 2 months ago.