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P0420 / P0442 / P0456 query

9K views 11 replies 4 participants last post by  eagleeye 
#1 ·
Hello all, I see some people have gotten excellent info and I hope I can get the same. I bought a 2005 Legacy, 2.5i, 135K miles that had the gaskets recently done. Timing components have not been a problem. After about 150 miles the check engine light comes on, the cruise light begins flashing but won't work. I was told the first code is catalytic converter and the last two are the gas cap. I have screwed on the cap tight and was told that it could be a loose seal on it or to replace the cap. I'm burning premium gas. My thought is that the first code could be O2 sensor(s) rather than the cc needing to be replaced. I'm taking it to my mechanic on Thu but are there any thoughts on this please? Thanks!
 
#2 ·
p0420 maybe a rear o2 sensor at this stage,...although other things produce it such as a a loose exhaust gasket before the last o2 sensor.

p0442 and p0456 both indicate of a minor evaporative system leak,...such maybe a hose or something in the area of the gas tank and the attached evap system that has become cracked overtime. be it a line, or a gasket, such are things mechanics diagnose and find when they are looking with the car on a lift.

I would suggest that you take the car to a automated car wash just before you drop it off, such makes the people that have to look at that kind of stuff happy. vs. digging through the road dirt, brake dust, tire smudge that collects on the items they are inspecting.
 
#3 ·
Thank you eagleeye. I saw the help you have given to others....you know your stuff!! I was told by the seller not to take the car to auto car washes because the equipment can damage the sunroof. I don't know where I can take it to have the engine cleaned off as I have moved to a new neighborhood but I'm sure my car obsessed neighbor does. Thanks!
 
#4 ·
no cleaning of the engine. if you got some dust on top of things just use a spray bottle of windex, or simple green if its greasy, armed with a rag in your hand, (spraying with any hose makes it too easy to hit something you don't want to hit with that much pressurized water).

previous owner hating automatic car washes....:frown2: ....them mechanics I know put their daily drivers in them sun roofs and all every week in winter time to wash the sand and the salt off, particularly the automatics when it is too cold to be standing with a hand sprayer.

does your sunroof or interior lights leak when you get heavy rain now? one might need some attention to make it stop,...but a car wash is no different to that kind of leak then a good hard rain.
 
#6 · (Edited)
I read a post a few weeks back with the same issues you have. You are getting the 420 code because you have a leak causing the fuel trim system to act up, dont worry about your catalytic or AF O2 sensors at this point. I would check the purge canister for leaks and then use a keen eye to follow the lines checking all the connections along the way. If you are going to pay for diagnostics have them start with EVAP leak testing

If you have been experiencing oil consumption check PCV
 
#7 ·
Has all leather interior and is like new and I checked the headliner carefully....no sign of leaking ANYWHERE in this car. Seller told me to make sure that I clean the track and area around the sunroof periodically with a little brush and I shouldn't have any problems with it. All lights work, including the ones in the doors. One issue that I will have is the salt water leaking from my boat(s) being carried on top. I can see the problems this will cause with the sunroof (which I didn't want). I need to get a sprayer to rinse them off before mounting them on top....

The car is very clean inside and out. New battery though one of the cables could be cleaner. All hoses are pliable and if not new, are in good condition.
 
#8 ·
According to CARFAX the car spent 80K miles in NY and has been the last 50+ in the Pacifc NW. But there aren't any rust issues, whew. Man, the car has been really dumped on--we've gotten a lot of rain lately--ever since I bought it last week. But it is stored in my garage.
 
#9 ·
ever smell fuel after a fill-up? If not, likely no holes in the filler neck.

exhaust leaks and tune-up issues can cause a P0420 - save replacing the cat as a last resort, often other issues lead to that code.

If the timing belt system components haven't been serviced in the last 9 years or 105K miles - they will become a problem - $$$bentvalves$$$
 
#10 ·
on my H6 car I am getting a p0442 code randomly, originally I was getting it when the tank as per the gauge on the dash had 1/4 or so in it. ...then it lost that pattern and would just come on.

no symptoms, smells, or changes in running. (have yet to rom-raider it)

just been canceling it for now, fix it in April or whenever snow tire season is over.

this is the first code this car has had EVER, and I have owned it since 2002 when I bought it with 15,000 miles as a corp. demo. 125,000 miles now.
 
#11 ·
No smells. Yeah, my mechanic told me it was more likely going to be something a lot cheaper/easier to fix than the cc. I bought some Cataclean to put into it but a mechanic friend of mine told me (besides joining this forum!) to not waste my money buying anything like that if it doesn't come in a can. He likes BG 44K but I couldn't find it so got Seafoam instead. But I'm holding off putting anything like that in there until my mechanic has a chance to look at it and besides, I'm not down to a quarter of a tank yet. A guy came into the store while I was returning the Cataclean and said the stuff just did the trick for his car. It costs $26 incl. tax. Seafoam is $14. I don't mind spending the money if it works though.

The problem is that the cruise control won't work as long as that check engine light is on. Wahhh....
 
#12 ·
the problems you got can not be fixed by anything like that coming in any can.

save your money and let the mechanic find the parts or leaks that need fixing.
 
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