P0450 - a story with photos and some questions

So the first time I fired up the 4Runner after the frame swap, I was driving home and after about 30 miles I was getting engine sputter and intermittent power surges, like I was running out of gas, even though I had a half tank.

I pulled over and saw this:


It’s raw gasoline pouring/dripping out from behind the engine bay near the steering gear. Not good.

I traced the gas leak to the EVAP vent hose, which I pulled up and out in this photo:



This vent hose usually attaches to the frame and vents inside the frame via a small plastic fitting. Here are a couple photos of the broken fitting from my old frame:




(If anyone knows the part number for this fitting, please let me know.)

My donor frame didn’t have this fitting attached and my old one was broken, so this vent hose was just more or less dangling freely, which actually made it much easier to find the leak. If it had been venting inside the frame, the gasoline would have likely been leaking further back (if at all) which would have thrown me off.

So I found the leak; that’s good. But why?! Why is there gasoline pouring out of my EVAP vent hose?!

Turns out two fuel lines were switched. Here’s a photo of the switched fuel lines, taken in front of the gas tank looking back:


I switched these two lines back to their correct places, crossed my fingers, and turned the key.

Everything started up and sounded good. I let it idle for a while to watch that EVAP vent hose and make sure no additional gasoline was leaking. After about 10 minutes, with everything looking good, I continue the drive home.

After another few miles I get a check engine light. I read the code and it’s a P0450:



I’m not surprised I get a EVAP-related code: gasoline was just pouring out of the charcoal canister! I clear the code and carry on.

Now it’s been maybe a hundred miles, and everything is running fine (other than a little valve lifter noise — a topic for another day…).

But this code keeps coming back about every 25 miles.


I don’t really know much about our EVAP systems. So, my questions:

1. Are there any negative side-effects or consequences by ignoring this code? (I’m in a no-inspection state, I’m really only asking about vehicle health.)

2. Is my charcoal canister ruined? Or will it eventually dry out?

3. Should I replace my canister? Pressure sensor? Both? Neither?

Thanks all. This forum is the best!!

NO issues, as you don't have TRAC/VSC that would be disabled with a check engine light.

Otherwise, just send it. EVAP system just recycles the vapors back into the fuel tank to prevent them from reaching the atmosphere.

As long as it's not pouring gas, just send it. The charcoal media is likely saturated with fuel, which will certainly cause an issue with the evap system. There's a few videos out there about rebuilding charcoal canisters (not specific to 3rd gen 4runners), that may be of some interest.

I wouldn't be concerned about it, but I would check for codes every month or so to see if you have any other codes going on.

Thanks [MENTION=80102]shadow247[/MENTION] , thank you [MENTION=319302]Bad Luck[/MENTION]

This all confirms what another mechanic told me. I really appreciate the help.

I might end up fixing this eventually because I hate the CEL but at least now I know it can be last on the list...

I used to get the "0450" code on a regular basis. Since the gas gauge didn't show full after topping the tank, I was overfilling the tank. Now I add gas once more after the gas hose shuts off, then call it good. I cleared the code and have not had the code come in for about 3 months now. Just confirming what other people have said. I think I was saturating the carbon canister.

Could be 77775-35010 is the one you need.

HiLife said:

Could be 77775-35010 is the one you need.

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I think you're right!!

EDIT: and after looking at the parts diagram, it looks like my EVAP breather vent hose is on upside-down. The shorter rubber length with the more pronounced hook shape attaches to the outlet on the charcoal canister. That explains why it was a little hard for me to clip the hose into place properly...

Well, it all depends what kind of smog laws you got in your area of the country. I know in California, you couldn't pass smog with those CEL codes, thus you can't register your vehicle. With the codes popping up every 25 miles, you might not be able to complete the drive cycle to reset the system to be ready for a smog test. As soon as they hook up their computer to your rig, they will quickly tell you you're not going to pass.

So, if your smog laws are similar, you can send it or not be worried about it until it becomes time to renew your registration. At that point, you're going to have to do something about it or deal with what happens when you have expired tags.

If you decide you're going to replace your Evap Canister, there's a guy, Josh, up in Washington that parts out 3rd and 4th Gen 4runners. I recently bought an Evap Canister from him for a 3.0 to 3.4 Swap project on a 2nd Gen 4runner. Josh is a good dude, sells parts for a very fair price and he ships quickly.

mtbtim said:

Well, it all depends what kind of smog laws you got in your area of the country. I know in California, you couldn't pass smog with those CEL codes, thus you can't register your vehicle.

So, if your smog laws are similar, you can send it or not be worried about it until it becomes time to renew your registration. At that point, you're going to have to do something about it or deal with what happens when you have expired tags.

If you decide you're going to replace your Evap Canister, there's a guy, Josh, up in Washington that parts out 3rd and 4th Gen 4runners. I recently bought an Evap Canister from him for a 3.0 to 3.4 Swap project on a 2nd Gen 4runner. He's a good dude and ships quickly. Josh is a good dude, sells parts for a very fair price and he ships quickly.

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Thanks Tim! If you have any contact info for Josh, please private message me if it's not too much trouble.

As far as registration, I'm in a no-inspection state. No smog checks, no safety inspection, nothing. I just pay online once a year and they mail me new tags.

Anyway, I also just want to thank you for all your videos! They are truly invaluable.

cl4Rk said:

Thanks Tim! If you have any contact info for Josh, please private message me if it's not too much trouble.

As far as registration, I'm in a no-inspection state. No smog checks, no safety inspection, nothing. I just pay online once a year and they mail me new tags.

Anyway, I also just want to thank you for all your videos! They are truly invaluable.

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You're lucky you don't have to deal with smog checks.

Here's a link to PNW 4runner Connection:
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Great to hear you're finding our videos useful.

So, the P0450 said very clearly that there was a malfunction in the EVAP Pressure Sensor circuit.

Well... guess what?! My EVAP Pressure Sensor was not plugged in all the way!! LOL

Now, my charcoal canister is still toast from getting saturated with raw gasoline, so simply plugging in this sensor won't solve all my EVAP issues. But still... it's a good lesson for me to remember the next time I get a CEL or some other symptom!

cl4Rk said:

So, the P0450 said very clearly that there was a malfunction in the EVAP Pressure Sensor circuit.

Well... guess what?! My EVAP Pressure Sensor was not plugged in all the way!! LOL

Now, my charcoal canister is still toast from getting saturated with raw gasoline, so simply plugging in this sensor won't solve all my EVAP issues. But still... it's a good lesson for me to remember the next time I get a CEL or some other symptom!

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Funny story, when I was doing my f150 tank I switched the exact same lines.. Same exact thing happened truck started stalling and gas poured out of frame. Instantly knew what I had done switched the lines on the side of the road and pulled the evap canister out, i must of shaken a gallon of gas out of that thing before nothing was coming out.. Truck runs fine now though no codes so far.. Always a fun time getting covered in gas on the side of the road, I’m just glad my truck didn’t burn to the ground.

T4topher said:

Funny story, when I was doing my f150 tank I switched the exact same lines.. Same exact thing happened truck started stalling and gas poured out of frame. Instantly knew what I had done switched the lines on the side of the road and pulled the evap canister out, i must of shaken a gallon of gas out of that thing before nothing was coming out.. Truck runs fine now though no codes so far.. Always a fun time getting covered in gas on the side of the road, I’m just glad my truck didn’t burn to the ground.

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How many miles since that happened?

And yes it's very fun getting covered in gasoline on the side of the road. For some reason I was surprised when gas poured all over me when I pulled those fuel lines LOL. Anyway, I now keep a fire extinguisher mounted in front of the driver's seat.

cl4Rk said:

How many miles since that happened?

And yes it's very fun getting covered in gasoline on the side of the road. For some reason I was surprised when gas poured all over me when I pulled those fuel lines LOL. Anyway, I now keep a fire extinguisher mounted in front of the driver's seat.

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Maybe 300 miles ago or so, I don’t drive it much as I have a separate DD. I was surprised at how much was coming out of the lines too lol.

Following up after about a week of driving after reconnecting the EVAP Pressure Sensor.

So far I haven't seen any CELs or DTCs or had any symptoms at all. This mirrors [MENTION=271883]T4topher[/MENTION] 's experience of no symptoms or codes after switching the fuel lines back to their correct positions. (Different vehicle, I know, but it still seems relevant.)

So, I think I'll just leave well enough alone.
I won't worry about my EVAP system until I start experiencing symptoms or see a DTC.

But I'm still curious about this. I guess flooding the charcoal canister with gasoline didn't cause any long-term issues? Did the gas in the canister just evaporate off and everything is fine now?

I 'overfilled' (kept pumping small amounts) Before I knew this was a No-No a few years back.

I did get some slight issues with filling up for a couple months (learned it worked better if the pumping side was physically lower pavement than the other side) and of course stopped pumping after one attempt after the auto shutoff took place, so like you it apparently 'healed' itself through drying out.

All is good now several years later, whew! Glad the system is robust enough to handle this. Luck.

cl4Rk said:

But I'm still curious about this. I guess flooding the charcoal canister with gasoline didn't cause any long-term issues? Did the gas in the canister just evaporate off and everything is fine now?

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Most likely the gas in the charcoal canister evaporated off and was burned with the gas vapors from the fuel tank whenever the EVAP purge valve was commanded open by the ECM. I'm sure it wasn't healthy for the charcoal canister, but it most likely won't be an issue anytime in the near future. Charcoal canisters do deteriorate with age. If you shake it and it sounds like loose sand/dirt/pellets then it should be repllaced.

Bad Luck said:

Most likely the gas in the charcoal canister evaporated off and was burned with the gas vapors from the fuel tank whenever the EVAP purge valve was commanded open by the ECM. I'm sure it wasn't healthy for the charcoal canister, but it most likely won't be an issue anytime in the near future. Charcoal canisters do deteriorate with age. If you shake it and it sounds like loose sand/dirt/pellets then it should be replaced.

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Thanks everyone.

I just gave the canister a couple good shakes and didn't hear/feel any loose sand/pellets move around, so given that along with the lack of symptoms and lack of DTCs, I think I'm good for awhile.

jgue467 said:

I 'overfilled' (kept pumping small amounts) Before I knew this was a No-No a few years back.

I did get some slight issues with filling up for a couple months (learned it worked better if the pumping side was physically lower pavement than the other side) and of course stopped pumping after one attempt after the auto shutoff took place, so like you it apparently 'healed' itself through drying out.

All is good now several years later, whew! Glad the system is robust enough to handle this. Luck.

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This was my situation, also. No "0450" code for about three months, with no glaring after effects.