Well, it has been more than 9 months and 550+ miles since last December's repair. All was well until the Check Engine Light came ON about a month ago, with code P0440, less the code P0441 than in last December. This time I had another issue which was the exhaust pipe section that has the O2 sensor fitted on had too many holes and break outs, so I chose to replace that mid section pipe first (refer to my DIY post at https://www.clublexus.com/forums/rx-...ed-advice.html).

Then I cleared the code and now it has been more than 2 weeks and 50+ miles: no CEL and no P0440 code.

I know that experts on this thread explained in detail that code P0440 has nothing to do with exhaust leaks, how ever severe the leaks might be. I am just reporting intermediate results back here and cross my fingers for P0440 not coming back - it was so difficult to diagnose.

 

Good luck. How is that rust repair holding up?

 

The car has logged another 200 miles and the repaired middle section is as solid as it was on day-one. I think the trick is to leave the rusted pipe as much as you can and let the new section go over them so to increase the structural strength since no professional welder was involved. If the remaining ends were long enough exhaust pipe clamps would work too.

The JB Weld paste would still release ugly smells when heated after 200 miles. But now the smell appeared all gone - an indication of being fully cured?

 

That's great news. I hope it lasts. I've never had great success with JB Weld but maybe the jobs I tried it on were not a good fit

 

maxSteel:

I applied JB Weld paste to seal potential leaks of friend's DIY welding. It is doing better than other paste type high-temp exhaust pipe sealer. High-temp silicon sealers don't hold much long from pressure if there are leaks (my prior experiences) in similar circumstance. I am not sure about relying on JB Weld paste for strength.

I will report back in a year also after more miles with photos of the repaired mid section.

 

Hi maxSteel: I just updated my last October's repair on the mid section exhaust pipe at
https://www.clublexus.com/forums/rx-...l#post11551310
with photos taken a few days ago. After nearly 1k miles (local paved streets, express ways and some highways) since, the repair is still holding up strong.

I remember you asked so to let you know my update.

Thank you for sharing your expertise.

 

I am replacing the charcoal emission canister assembly, due to codes P0440 and P0446. There is a (relative) large tube that has a "special" locking mechanism that I don't know how to release the end.
Please advise.

 

Somebody posted this. Will look for it. I think you push it in and squeeze, then pull out

edit: It's on page EC-9 of the Evap Testing guide you've probably already got https://www.clublexus.com/forums/rx-...ml#post2218270

Did you test the canister and VSV's?

 

I had P0440 P 0446, suspected a leaky overflow valve on top of the gas tank and bought it, but the shop did a smoke test and said canister leaky. Replaced charcoal canister and both solenoid valves, did not fix the problem. Wasted a lot of time and money with 3 repair shops.

Lexus dealer quoted $150 diagnostic fee applicable to any repairs. Found Dynamic Auto Repairs in Fountain Valley CA, owned by an ex Lexus Master Tech. He had diagnostic software on his laptop that can turn on and off EVAP components individually. After 20 minutes he confirmed a very small leak at the overflow valve.

The valve costed $57, he charged $400 for labor. All OBDII flags cleared, EVAP test passed on the drive back.

If you are not familiar with how to remove the big hose, it may break, Better let the pros do it.

 

Couple of things to note...

If there was leak detected by smoke test, as the known leaks are fixed, re-testing is necessary. There can be multiple leaks and the tiniest leak needs others to be patched up first.

There is always a need and a time for expert repair facility. Locate one or at least have a name of a good one in your diary.

Salim

 

Thank you Salim and CPTSOLO, for your advices. First, allow me to finish on replacing the Canister. I was not able to release the "big" tube by hand with squeezing the "releasing" tabs - the plastic is so hard or my fingers don't generate enough force. So my next option was to insert the flat head of a small screw drive between the port's tube and the locking clip and use another hand to pull and wiggle the connecting tube's end and then similarly work on the other locking clip. The connecting tube then came off from the port terminal.

The 2 locking clips are designed to secure the connection end on the port's shoulder ring.

Here are 2 photos of the replacement canister being installed:


I purchased the Toyota/Lexus OEM replacement canister on eBay and it toke 2 weeks to deliver from Japan:







Here is a link to the vender with which my purchase for $220 was made:
https://www.ebay.com/itm/125569267253
It is yet to know how this replacement canister works out; if there is any issue I will report back.

Now, onto why I moved to replace the canister box. The P0440 and P0446 codes came up about a year ago. With the advices by Salim, maxSteel and others on this thread I did vacuum test with a hand pump with the guidance and instructions of the PDF docs (also on this thread). I could not find any vacuum leaks. But, at the time, but cleaning up a stuck check valve just outside the air cleaner box's wall, the CE light was gone. So, all went well for a little over 500 miles, then the CE light and the same codes came on and back again. I cleaned the same check valve again and all was well again for another 600 miles. Then the same happened early this summer. This time my old trick did not work and CE light and codes came on and back in less then 20 miles.

As I exhausted my skills, I took the car to my local Toyota dealer . A technician there did smoke test and replaced the gas tank's refill neck. This costed me over $1.1k. 15 miles later, CE light and P0440 code came on and back. Took the car to the same dealer. What I was told is that the canister need to be replaced (a $400 replacement part); potentially and likely, a check valve on top of the gas tank need to be replaced. For the latter, it would require to take down the gas tank, a 3-4 hours job. On a $185 per hour lab cost, this second round fix would take another over $1k. So, my instinct is to replace the canister first, a DIY job I could do, and see what happens next.

So, this is the background of my replacing the canister.

 

This is a follow up on my canister replacement: the same code came back after 25 miles. I took the car back to the local Toyota dealer, whose technician replaced the gas filler cap with a Lexus part for $70 and told me that there is no more leak being detected. The older cap was an OEM part purchased on Amazon a little more than a year ago, one of the first things I did when the PO 440 and PO 446 codes came up on this car.

Now the car has logged 140+ miles after the Lexus gas filler cap replacement and so far no CEL. Maybe the devil was the cap for all this time; hard to tell.

 

With leaks it is always be the last leak which when fixed, you will be good. Before that you can keep fixing as many leaks as you may have minus 1 (the final one).

Saloim

 

Thank you Salim, for your comments. I agree with you, in theory. In practice, there is always the question: which one to go-after first? Or, pick the right one to go-after first.

In retrospect, I had placed too much trust on the first OEM gas tank filler cap replacement (a little more than a year ago) from Amazon. The dealer didn't show me the old filler neck ...... I tested the old canister a couple of times when it was still on the car and could not find any leak ......

I hope my this experience leaves some reference values to others in similar situations in the future.

 

Hi i was referred to this thread by someone because I was looking for help on code p0446. I checked the charcoal canister and all the hoses there were connected did see any gas leaking from any of the hoses but it was pretty old down there and there was a little bit of spider webs. My miles per gallon have decreased a good bit i tried clearing the code and tightening the gas cap tighter back in december and the code just came back and my car would smell like gas when i was parked it and turned it off. The smell mostly comes from the engine bay, does anyone have any tips on what i should inspect particularly that could be the culprit of such problem? Please and thank you