HankMan64

I have a 2019 ES350 with about 19k miles on it. About a week ago I got a check engine light for a lean condition on only bank 2. Upon checking the data with a tool I confirmed both banks were in the high 20's. I did some basic research and found that a dirty MAF may cause this issue so I cleaned it and reset all codes. Things were fine for a few days then the code returned, P0174 and P0171, this time it was for both banks. It also gave me codes P0455, P0441 (this is the only and only time I got these codes) and P0505. I re-did my gas cap and cleared the codes and again for a more few days it was fine. I noticed that Bank 2 consistently ran leaner even within normal ranges so I was thinking maybe a dirty injector. I bought and added someRedline S-1 before filling up and drove it on a 3 hour each way trip. I drove the car around town a small amount while there and then home without any issues or check engine lights. Once I got back home and was driving home from work I noticed a high idle on startup, checked the data with my tool and both banks were in the 30's again. Shortly after it tripped my check engine light again, P0174 and P0171. It also always triggers a Parking Support Brake Malfunction message at the same time the check engine light tripped but I didn't notice any issues. I noticed that when accelerating even moderately the LTFT's seem to improve dramatically but then when I left off the gas they returned to their elevated state. The next morning heading to work upon startup and the first 5 or so minutes of my drive LTFT's on both banks were still in the 30's but then it seemingly randomly started dropping to normal levels around 3 on one bank and 7 on the other. I know these aren't ideal but also are far better than what I'm getting when the issue occurs. The LTFT on both banks will be very lean normally around 38-39 for some period of time and then on it's own drop down to around 3 on bank 1 and 7 on bank 2. This ranges from driving just a few minutes down the road to maybe 20-30 minutes of driving. I live near my work so don't drive very far distances in general. It doesn't seem to me that the issue occurs when the engine is only cold or hot or on the first start of the day, seems to be fairly random but it's occurring more frequently than originally.

Today the issue occurred after making a shorter drive during the day and then starting the car back up about 30ish minutes later. There was a noticeably high idle so I checked the data with my tool and it was in the high 30's. During my drive to get lunch I noticed again that when accelerating both LTFTs improve dramatically to near normal levels then returned to high 30's under no load. I checked the codes and this in addition to my P0174 and P0171 codes I also had a P0505 for idle air control system.

I noticed for about 45 seconds I had a steering wheel warning light with an exclamation point on the bottom left of my dash during startup after lunch but then it disappeared and never returned. While driving back to work from lunch after about 6 minutes the LTFTs start improving on their own and settle out around 3 and 7 respectively. This didn't turn off either check engine light on my dash but the car responded better and didn't have a elevated idle. Luckily this time I had a scan tool hooked up recording all of the data during this period so I am able to review it all from my tool. I can clearly see when the LTFT's fix themselves but not sure what else I should be looking at during that same period. Unfortunately I don't believe my scan tool allows for the data to be exported but I am able to graph out 4 items together. I could take a video or check the data myself if anyone has suggestions on things to check.

I am out of my depth on this issue, given how it's intermittent and "fixes" itself I am not sure where to start looking. I am thinking about taking the car to a local Toyota dealer (Nearest Lexus dealer is 4 hours away) to see what their diagnoses is but honestly would rather fix it myself. I would greatly appreciate any input or suggestions. I am more than happy to check/post any data that would be helpful in diagnosing this issue or complete other testing etc. I am fairly mechanically inclined just not used to working on such a new car. Thank you for your time!

grp52

You may want to take a look at Technical Service Bulletin (TSB) L-SB-0005-23, February 9, 2023, Fuel Pump (Loss of Fuel Pressure) (pdf) with an introduction of:
(In case you don't know it, Malfunction Indicator Lamp (MIL) ON is AKA check engine light on.)

If repair cost is a concern, if your ES's problem is indeed the issue addressed by the TSB, the TSB states the repair is covered under the 72 months or 70,000 miles Lexus Powertrain Warranty.

minotaar

Out of curiosity what is a “system too lean” condition?

grp52

For a general explanation, this Long Term Fuel Trim and Short Trim Fuel Trim article looks to cover the bases.

For Lexus ES specifics, you can search the lexusguide.net Lexus ES (XZ10) Service Manual on one of the P0171 or P0174 codes. Amongst the search results, digging through the information on the System Too Lean Bank 1 (P017100,P017200,P017400,P017500,P117000,P117B00) page will give you a good idea on what it means specific to the ES 350 engine and the means of monitoring and determining when a "too lean" code is set.

HankMan64

Thank you for your response! I believe that previously this pump may have been replaced, I am showing that 10/7/2020 it had service items "Replace Low-Pressure Fuel Pump". Do you by chance know if this the same pump being mentioned in this TSB? I noticed that this TSB is from fairly recently long after that work was completed so that may be something to look into still.

Yesterday after filling up my car with gas it wouldn't start. I waited about 10-15 minutes and it started up but was a very hard/rough choppy start followed by a high idle about 1500-2000 rpms. I let it idle for a few minutes and it fell to about 1000 rpms so shifted into drive and made my way to work. I moved the car once at work after about 1-2 hours and it started right up no issues at all but still had an elevated idle.

After doing some more research I have found a few other people with the 3.5 V6 that experienced very similar issues and data from a failing (intermittently it seems in my case) Vapor Canister Purge Valve / Solenoid. I am hoping that this may be my issue as well so I ordered the part and plan on replacing it as soon as it comes in. Thankfully this part is located in a very easy to access/swap location as well. I had all of the following codes in the system and will not be driving it again until I get it replaced to hopefully resolve my issues.

Codes: P0505, P0174, P0171, P117B

HankMan64

I am happy to report that replacing the Vapor Canister Purge Valve / Solenoid seems to have resolved my issues! My idle issues have disappeared and fuel trims have stayed within an acceptable range with no CEL's or codes in the system. I have done a mix of highway and city driving since as well. I hope this will help others in the future. It is a very simple part to replace, took under 10 minutes total and is right on top of the engine. Rock Auto had the best price for mine.

My part was: Vapor Canister Purge Valve / Solenoid STANDARD MOTOR PRODUCTS CP808 (https://www.rockauto.com/en/moreinfo...&pt=4936&jsn=1) OEM / Interchange Numbers: 258600P030, 258600P090, 2586025010, 2586031110, 2586036111, 2586037060, 25860F0010, 9091012283, 90910AC004, CP871, CP954, CP988, CP992, CP994

Please check to make sure you order the proper part for your make/model, I have a 2019 ES 350 UL.
Best of luck!

rj9393

Has the issue popped up since replacing the Vapor Canister Purge Valve? I'm having this same issue. Lean on 1,2 intermittently. P01441 codes on and off. ITs been happening for some time now and my idle is a bit rough, although no issues when im accelerating. I'm thinking of replacing this part based on your comment before i take it to a mechanic!