ISterguy

Started my 2013 RX this afternoon and it indicates these two alarms on the instrument cluster, Engine Check Light & Track Off. Found out that my gas cap was not tightened (let my son fill the tank when he borrowed it the night before). Hooked up my OBD II scanner to clear and it shows two codes P0441 & P0445. They reset but my scanner says they are permanent. What does that mean? Will stay as an error until the ECU says otherwise?

Clutchless

It may reset after driving a while now that the gas cap has been properly installed. Or they may stay in the memory.

ISterguy

Yeah, I will check again after my next refill.

mjeds

quick google shows you can reset these codes with a battery disconnect.


but I suspect they will go away once the emissions systems gets back to a ready status which can take 100-200 miles.

ISterguy

I have already cleared the fault codes with my scanner. I am waiting to see if they remain in memory permanent or will clear after the next tank fill. Thanks for the input mjeds!

nancy1212

Hi there! I've been reading through the different threads to try and get a handle on my issue. This forum is so incredibly helpful!!!! Thanks to all that contribute! I have a 2010 Lexus IS250 and my CEL and Traction off light came on. The VSC light has not come on at all. I did as you all suggested and made sure the gas cap was tight. I put gas in and the next day, they lights went out. 2 days later they came back on so I ordered a new gas cap, put it on and the next morning when I started my car, the lights were out. I drove it a day and half and sure enough, both lights are back on again. I've only driven about 100 miles if that. Should I try taking the negative battery cable off and see if that helps? I haven't taken it to Auto Zone yet to have the codes pulled. I just find it odd that if it was the gas cap, why do they go out and then come back on??? Is that what happens if you haven't disconnected the negative battery cable yet??

ISterguy

Not real sure why your CEL & TRAC off light return once you have a new gas cap. It appears your problem is probably not as easy as a loose or bad gas cap. I used a OBD II scanner on my RX and cleared my fault codes (because of the tightened gas cap) even though it said they were permanent in memory. Some codes will not clear by just disconnecting the neg bat cable. I would suggest you have Auto Zone or the Lexus dealership read the codes to see exactly what is causing the lights to return. In the case of my problem I got codes PO441 & P0445 The Evaporative control system (EVAP) prevents gasoline vapors from the fuel tank from escaping into the atmosphere. The Evaporative control system catches and stores gasoline vapors in a small box installed near the fuel tank called charcoal canister. When you drive and certain conditions (speed, engine temperature, etc.) are met, fuel vapors are gradually purged from the charcoal canister and burned inside your engine. The code P0441 & P0445 means that the purge flow is lower or higher than it should be in these conditions. The purge flow is controlled by the purge valve (purge solenoid).

Once you get your code(s) google them on the internet and see what it the code given malfunction description is. If it's not the loose or bad cap it may be time for your service tech to look at it because it may be too technical for you to troubleshoot any further unless to are a car tech savy individual. Good luck...

nancy1212

Thank you ISterguy! I did as you suggested and went to Autozone. Super nice guy pulled the code and it was the P0101 code - ( Lexus Is250 P0101 OBD-II Engine Trouble Code is P0101 Mass or Volume Air Flow Circuit Range/Performance Problem.) He had me purchase CRC Air Flow Cleaner and he showed me how to do it - basically he just did it for me. It's not something I'd remember how to do or would feel comfortable doing myself! He reset the code and so far so good, it hasn't come back on. I gave him a fat tip for his troubles! The beauty of it is, he also has his own mobile mechanics business he is trying to get off the ground so I got his contact info and will certainly use him in the future! Thank you so much for your advice! I love this forum! Have a great week!

Marqevans

Just a further tip, make sure you or your son are not topping off the tank when you fill up as it will damage that evaporative system.

nancy1212

Forgive my ignorance Marqevans, but when you say to be sure not to top off the tank when filling up, do you mean don't continue to pump gas in like some folks do even after the pump shuts off... you know, like to continue to put gas in until you reach an even amount of money on the gas pump? I know I must sound so stupid, but I did not know that could damage anything! I generally don't do that but I have in the past. I want to be sure to tell my kids not do it either if that is a bad thing for a car!!!

Marqevans

Yes that's exactly what I mean. When the pump clicks off hang the nozzle back up and move on! There is some sort of evaporative device that gets damaged when you overfill.

ISterguy

Good to hear! I see your problem was not the gas cap after all. Your problem was a dirty mass air flow sensor located on the engine intake just after the air filter.

Regarding the tank fill up thing ...... I have always filled up just as you mentioned (max top off or rounded off to an even amount) and have NEVER experienced a problem in the last three cars (RX 350 IS 350 & GS 350) over the last 6 years! I also do not put hi octane premium fuel (only 87) and have not had any problems.

Marqevans

From page 109 of the 2015 RX Lexus owner manual:

When refueling
Observe the following precautions to prevent fuel overflowing from the fuel tank:
●Securely insert the fuel nozzle into the fuel filler neck
●Stop filling the tank after the fuel nozzle automatically clicks off
●Do not top off the fuel tank
■When replacing the fuel cap
Do not use anything but a genuine Lexus fuel tank cap designed for your vehicle.
Doing so may cause a fire or other incident which may result in death or serious
injury.
109
1-5. Refueling
1Before driving
NOTICE
■Refueling
Do not spill fuel during refueling. Doing so may damage the vehicle, such as causing the emission control system to operate abnormally or damaging fuel system components or the vehicle's painted surface.

Clutchless

The excess gas from overfilling could back up into the charcoal filled canister that is supposed to catch gas fumes evaporation, the liquid gas could damage it, cause a check engine light and / or other emissions issues that may show up during testing. Although covered by the long emissions warranty, If you are found to be at fault by overfilling the tank, those charcoal canisters can run a few hundred bucks to replace. Having said that, I think it takes a lot of overfilling to reach that level of gas. I would think that topping up to meet the next even amount would not be enough to create any risk of harm to the canister.