CEL On and VSC Off Blinking 2008 AWD LTD V8

[LEM]

Yesterday the weather turned cold, like from mid-40s to mid 20s. We had just returned from a 2200 mile trip to Florida. When I started our 2008 4Runner LTd V8 AWD, the CEL came on and stayed on, the VSC Off light blinks, and one other light just below the VSC Off lights showing a car on two squiggly lines also came on and stayed on.



I took it to Advance Auto and they checked the codes. It showed a minor leak in the emissions system, indicating that the gas cap was loose. I tightened it several clicks after the codes were cleared and it was fine.

I drove it to work this morning with no issues. At lunch I started it up and the same lights came on. It's even colder today at about 20F.

Question: what else could be causing this? I will stop at Advance Auto to have the codes checked and cleared again, but i would like to understand this better.

Thanks.

[Brian R.]

You may have a loose hose or leak. What code was displayed?

[LEM]

I stopped by Advance Auto again to have the codes read and cleared. Codes P0441 and P0455 showed up, both having to do with the evaporative emissions system. They cleared the codes and so far so good. The guy there mentioned that I shouldn't top-off the tank as this can fill up a canister underneath the vehicle that serves some kind of emissions purpose. I regulalry top off, especially when towing the camper as I can usually get 2-3 more gallons in the tank by doing so. Stupid emissions nonsense! I wish the EPA would just go away!

[Brian R.]

They may be right about the source of the trouble code, but there are many other possible causes. The EVAP system is one of the most complex systems in the truck. If you don't solve the problem by not overfilling, and you want to troubleshoot it yourself, come back and I can give you some additional possble sources of this code.

[fourwd1]

Originally Posted by Brian R.

T... The EVAP system is one of the most complex systems in the truck. ...

You have that right.
They can get screwed up to the point that raw gas is leaking from the canister. A bad vacuum line is a frequent problem.

[LEM]

Originally Posted by Brian R.

They may be right about the source of the trouble code, but there are many other possible causes. The EVAP system is one of the most complex systems in the truck. If you don't solve the problem by not overfilling, and you want to troubleshoot it yourself, come back and I can give you some additional possble sources of this code.

I'm pretty certain that the gas cap is securely seated, so I'm ruling that out. The vehicle ran without a glitch all day yesterday after having the codes cleared on Tuesday night. But this morning the trouble lights came back on, so I'm going to stop by Advance Auto again to have the codes checked and cleared. I presume that I will see the same codes: P0441 and P0455.

So, aside from the gas cap, what else should I check?

I thought I would crawl under the vehicle and try tracing the line from the fill tube to the evap canister to see if I can find any cracks or loose connections. The vehicle is only 3.5 years old with 45,000 miles and is garage-stored, I would be very disappointed to find a deteriorated rubber hose already.

If it is the canister, how can I verify it and what can be done to correct it?

Thanks for the help!

[Brian R.]

A. Diagnostics for P0441:
1. Remove and replace Vacuum Hoses between EVAP VSV (vacuum switching valve) and Charcoal Canister. There may be a cracked hose or loose connection.
2. If there is a metal vapor pipe between EVAP VSV and Charcoal Canister, clean inside of vapor pipe.
3. Replace EVAP VSV and Charcoal Canister assembly with new parts.

I don't have any information yet on P0455.

Download a service manual for an '06 4Runner here.

[LEM]

I spoke with an independent repair shop and they told me that the P0441 and P0455 codes are pretty generic, though they do point to the evaporative emissions system. He recommends having the codes read by a Toyota factory scanner, which is in line with what the dealership told me earlier this week. So I'm going to take it in and get the specific Toyota codes and hopefully a definite path forward on the repair. I do hope it's a simple (and inexpensive) fix.

I'll post the results once I have them...

Tonight I will get under the vehicle and do a visual inspection of the hoses and connections, perhaps I'll find the problem on my own!!!

Wish me luck, or better yet, send up a prayer!

Thanks.

[LEM]

Well the shop scanned the 4Runner and came up with the same two codes (P0441 and P0455), but said they were able to pinpoint the problem being with the vent valve on the charcoal canister assembly. Unfortunately, the vent valve cannot be replaced by itself, apparently it's an integral part of the whole assembly, which costs $900! I had them clear the codes and am going to wait this out a bit before shelling out that kind of dough for a nuisance EPA code.

I may look around on eBay and in local junkyards for a used assembly, the labor seems pretty basic to replace it.

I still may take it to the dealer and see what they say.

[Brian R.]

Yes, definitely get another opinion. There are too many possible causes for these codes.

[LEM]

Since I had the codes cleared at a local shop (not an Advance Auto or Or'Reilly's) last Friday at 2:00 PM, I have put about 70 miles on the vehicle over four or five trips, and so far no trouble lights. I am cautiously optimistic.

A friend who owns a Sequoia told me that he thought the ECM had a program that prevented repeat codes from appearing within a certain timeframe. I'm hoping that this is not the case. Even if it is, I think I have gone longer this time without a repeat code than when I had it cleared before at the auto parts store.

God willing, there is no damage to the vent valve or other components of the evaporative emissions canister module and my T4R will run error-free for many more years!

I hope that this is the final entry, at least for me, on this thread.

C-ya!

[LEM]

After about 200 miles, the CEL and VSC Off lights came back on Friday morning. I will have the dealer check the codes and if they tell me the same thing about the vent valve on the charcoal canister assembly, I guess I'll have to bite the bullet and find one.

Anyone know of a good, reputable source for Toyota parts?

[Brian R.]

http://www.rockauto.com/

http://www.napaonline.com/

http://www.1sttoyotaparts.com/index.php

http://www.toyotapartscheap.com/

http://www.partswebsite.com/toyotaandlexusparts/

[LEM]

Toyota scanned the DTCs and found only one: P0456, very small leak in evap system. They did not see the P0441 or the P0455 that Advance, O'Reilly, and an independent shop saw. The Toyota tech suggested that it might be the check valve in the gas cap, and because I could get a factory gas cap for $15, I replaced the original one. They cleared the code for me and did not charge me for the scan, mighty nice of them.

The last time the codes were cleared, they did not show up again for about 200 miles. I'm hoping that was a function of the gas cap check valve sticking intermittently and not a ECM programming design.

[LEM]

Well, after 300+ miles and one full tank of gas, so far so good...I'm cautiously optimistic that the problem has been resolved. In this case, I'm very glad I went to the dealer...the independent shop had me travelling down a road that would have cost me $1100 instead of $15!