1998 Eldorado......Made an appointment to replace exhaust system. While I was waiting to have this done my Service Engine Soon light came on. Code P0446 EVAP etc. The shop replaced my exhaust system (except for the cat.) They replaced the Vent Solenoid Valve. That was three days ago. This morning Code P0446 is back together with the Service Engine Soon light. Any idea what they missed? I want to go back and tell them what to check. I realize they should know but they are not a Caddy shop so if I can give them a lead I will.

You might also check the gas cap. The evaporative system all ties together in a loop from the gas tank to a canister which bleeds off to the intake manifold to burn accumulated evaporation vapors. My '02 had a recall for a fuel tank pressure sensor, same system. Some in here have had trouble with a rusted out fill pipe to the tank.

Thanks Submariner. Think you may be right. I realized today that when I reset the light it stays off until I get gas. As soon as I leave the gas station it comes on again. I drove about 95 miles today and the light never came on.
I'll pickup a new cap tomorrow. That's a cheap fix. Thanks again.

Well, I'm still fighting this damn code. New exhaust system, replaced vent valve, new fuel filler pipe, new gas cap. My inspection is due in Sept. so gotta find a solution. Also going to a new garage next week so hopefully he will find the cause. Any ideas what else we could check?

Mitch,
I had a feeling that the gas cap wouldn't cure this code, a faulty gas cap useally sets DTC P0440, Evap large leak. Now in your case it’s going to be a little difficult to diagnose without a scan tool. But, we'll give a go.

This code can set because a blocked or restricted EVAP Vent Valve or vent path. The ECM/PCM is timing how fast the evap system can release the vacuum in the gas tank durning a self diagnosic test. If the EVAP system fails to release the vacuum quickly enough, this code sets. Remove the hoses from the evap canister and look for black carbon particles, it you see this contamination in the hoses then they have caused a restriction in the system and the cansister will have to be replaced along with a cleaning of the pipes and hoses. Inspect the vent valve hose that leads to freash air (the vent hose) for a pinch or restriction. Or, a faulty fuel pressure transducer (FTP) sensor can cause this code too. Good luck.

Thanks Frank. I'll turn this over to my new mechanic and see what he can do. I think this is a really stupid question but does the thermostat or coolant system have any relationship to this problem. I read something which I probably misunderstood indicating you should check the gas cap, the coolant res. cap, and the thermostat. I ask this because the car is going in next week for a coolant flush and thermostat change. I thought I was having HG problems but this guy is 99% sure I'm not. He spent about an hour checking it over yesterday. I didn't get into the EVAP problem with him. I'll hit him with that next week.
I think it's time to get rid of this car as much as I love it. Just too many problems for me to handle at my age and getting too expensive for my Social Security check to digest. Maybe I'll put my order in for a SMART4TWO

Mitch, the EVAP system stores and then burns gas fumes from the tank so as not to vent them to atmosphere. It is completely independent of the cooling system, so the surge tanks cap and thermostat have nothing to do with it.

Maybe I'll put my order in for a SMART4TWO
Oh say it ain't so.

Maybe I'll put my order in for a SMART4TWO

Mitch,
I can sense your fustration, but. A SMART4TWO are you sure? How much are going spend on that car and how trouble free will it be after it's out of warranty? I'm betting you are some what spoiled from the Eldo and once you get in the smart4 you will miss her.
Now, you have a lot of spent extra money on this repair because it has not been propely diagnosed. My guess, sombody has just been replacing parts because they don't have a FSM, scan tool, or evap cart. I've seen P0446 repaird by removing a spider web in the vent hose. That's a very inexpensive repair. so far, vent valve,filler pipe, and gas cap were not needed because the code is still present. Only a couple of things left that can cause this code, FTP sensor, restricted vapor cansiter, pipe or hose. Good luck, don't make a rash decsion because of this code. If you didn't need the state inspection you could continue to drive the car until you found a good caddy tech. Take Care, Frank

Ah come on guys!! Doesn't a little part of you wish you had a Smart for maybe a 2nd car to run out for a 6 pack? They really look like fun (for a 2nd car). Yes I still want my Eldo. By the way,,,about two blocks from my house there's a '54 (I think) Caddy for sale, pink and white. Also about two miles from here there's a 71 Seville with the sweep back. All of a sudden there seems to be a run on old Caddies. Well I'm getting off track from the P0446 problem so I'll let you know how much my next visit to the car doctor costs me. That's next Thursday.

[quote=Mitch3;1619246]Ah come on guys!! Doesn't a little part of you wish you had a Smart for maybe a 2nd car to run out for a 6 pack?
UHMmm I don't know, I rather have have a 68GTO to do that in. Wait, I do have a 68 GTO so I'm all set. ;)



Well I'm getting off track from the P0446 problem so I'll let you know how much my next visit to the car doctor costs me. That's next Thursday.

OK, good luck, hope they get it right the first time! Don't forget to let us know what the fix was. :cheers:

OK GENTLEMEN WE HAVE A FIX... $2000 later and we have the answer and we have a much better car I think. I also have a NYS Inspection. OK ready?????
MICE MICE MICE...As a last resort we dropped the fuel tank to replace the FTP Sensor. What the Hell is that??? A mouse nest!!! The little buggers ate the wiring going to the FTP. Fixed the wires. Problem solved. I just bought some Rampage Bait Chunks and put them in the door wells, under the hood, in the trunk, glove compartment and anywhere else the dog wouldn't get them. As the song says TIS THE SEASON TO BE JOLLY AND TO KILL MICE. Everyone...Check your cars....Thanks to all and to all A GOOD NIGHT....Mitch

OK GENTLEMEN WE HAVE A FIX... $2000 later and we have the answer and we have a much better car I think. I also have a NYS Inspection. OK ready?????
..Thanks to all and to all A GOOD NIGHT....Mitch

Mitch,
2K for an FTP Sensor and repairing the 3 wires that go to it? :holycrap:
Anyway, I'm glad it's fixed.
FYI, you might want to check with your auto insurance some will cover this kind damage. Enjoy your caddy, take care, Frank

Maybe you should lease a hungry cat to the car when you park it. I keep mouse traps by each corner of the 3 garage doors as well as the service door and in the corner of the garage. I generally kill at least a half dozen each fall. Which reminds me, time to rebait them. They be looking for a warm place to winter soon. I also put a few along the foundation wall just below the floor joists. Haven't had one in the house since I started doing that 20 years ago.