maxSteel

It's certainly possible. Good luck.

cwatx

Hi gomeybear,

Did you decide to have Lexus of Austin replace your rollover valve? If so, did it resolve your problem?

I'm in a similar situation. I've been getting solely a P0440 code for the last 9 months or so. I've tried a new OEM fuel cap but that made no difference.
When I reset the code by disconnecting the battery, the CEL doesn't come back on for ~800 miles or so, but it does keep coming back on.

I haven't had any degradation in performance, so this hasn't been a big priority to fix; however, my inspection is due in Nov so I need to get it taken care of.

maxSteel

800 miles before it comes on again seems like a lot. The emissions test cycle should be complete in a few days.

I also let it drag until I needed to get it inspected, and changed the fuel cap without success.
I finally tested things out according to the diagnostic and the canister tested bad. No problems since I replaced it.

gomeybear

I did have Lexus of Austin replace the rollover valve. Not sure if it has solved it. Ill have to wait and see after about a month if the CEL doesnt come back before then ill say it solved it. As for yours not showing up but every 800 miles I would say to check into an intermittent electrical connection issue to the various VSV's iinvolved in the emissions system.

cwatx

Thanks for your replies, maxSteel & gomeybear.
maxSteel - when your canister was bad, did you just have a P0440 code?

It does seem interesting that when I clear the P0440 code by unplugging the battery, I get anywhere from 500 - 1200 miles without the CEL coming back on; however, if I clear the code with the code reader, I only get ~100-200 miles before the it comes back.

I guess I need to bite the bullet and go get it diagnosed.

maxSteel

I don't recall the code, sorry.

When you clear the code it goes through this long cycle of driving at different speeds before it comes back, see attached.
Disconnecting the battery clears stored trim data which may affect the timing.

Page 15 of that readiness document lists preconditions that will affect the timing. I especially like the 2nd one.

Drive Pattern Preconditions (for the Evap monitor)
The monitor will not run unless:

• MIL is OFF.
  
• Fuel level is between 1/2 to 3/4 full (for faster completion).
  
• Altitude is 7800 feet (2400 m) or less.
  
• ECT (Coolant Temp) is between 40F and 95F (4.4C – 35C).
  
• IAT (Intake Air) is between 40F and 95F (4.4C – 35C).
  
• Cold Soak Procedure has been completed.

cwatx

Hi gomeybear,

Has your CEL stayed off since you had your rollover valve replaced back in Sept?

gomeybear

Yes it has stayed off thus far.

cwatx

Great news - thanks