Evap Codes Troubles
Thread Starter
1st Gear
Joined: Apr 2025
Posts: 1
Likes: 0
From: california
Evap Codes Troubles
Got a 02, 300k on dash, stock motor, was rebuilt @215k
got p0420/430/440/446
no other codes car runs like a champ, but i currently can’t pass smog.
so far i replaced a good amount of vaccum lines, VSV switch, exhaust gaskets.
While at cold start or acceleration i smell exhaust smell in the cab.
i’m thinking that it’s the rollover valve or charcoal canister. My cats seem good no smoke or rotten egg smell. Just need some advice and help.
got p0420/430/440/446
no other codes car runs like a champ, but i currently can’t pass smog.
so far i replaced a good amount of vaccum lines, VSV switch, exhaust gaskets.
While at cold start or acceleration i smell exhaust smell in the cab.
i’m thinking that it’s the rollover valve or charcoal canister. My cats seem good no smoke or rotten egg smell. Just need some advice and help.
Last edited by userr; Apr 13, 2025 at 07:20 PM.
Driver
Joined: Jul 2023
Posts: 93
Likes: 10
From: MN
To get that EVAP code taken care of, if you've already been replacing the usual suspects, you might need a smoke test kit. The Ancel S300 and S3000 are pretty decent for a reasonable price, you'll save money over time buying one of those for a couple hundred bucks instead of parts-swapping until the issue goes away.
But, what other people aren't noting is that you're telling us you smell exhaust, not gasoline, in the cabin. Checking to see if your EVAP or EGR valves are stuck open is a good first step, but also, check for an exhaust leak, particularly before the O2 sensor. An exhaust leak in the manifold itself can throw those codes. Checking your fuel trims might be another good place to look - Is it running lean? Rich? Normally? While you're already checking your fuel trims, it's a good idea to check your O2 sensors and what information they're feeding the computer. If you don't already have a scantool, I actually have a basic $30 one that I take with me everywhere that can look at live data - AutoLink AL319 .
A lot of the time, you can find exhaust leaks by using a spray bottle with soapy water in it and spraying it on suspected leaky areas - The mating of the manifold and the head, the O2 sensor holes, places like that.
These sorts of issues actually can trigger P0420 even if your cats are good. Get that leak taken care of, then address the cats. Once you've taken care of that leak, you'll be able to better interpret live data coming from your O2 sensors and figuring out if your cats are actually bad or not.
Happy hunting!
But, what other people aren't noting is that you're telling us you smell exhaust, not gasoline, in the cabin. Checking to see if your EVAP or EGR valves are stuck open is a good first step, but also, check for an exhaust leak, particularly before the O2 sensor. An exhaust leak in the manifold itself can throw those codes. Checking your fuel trims might be another good place to look - Is it running lean? Rich? Normally? While you're already checking your fuel trims, it's a good idea to check your O2 sensors and what information they're feeding the computer. If you don't already have a scantool, I actually have a basic $30 one that I take with me everywhere that can look at live data - AutoLink AL319 .
A lot of the time, you can find exhaust leaks by using a spray bottle with soapy water in it and spraying it on suspected leaky areas - The mating of the manifold and the head, the O2 sensor holes, places like that.
These sorts of issues actually can trigger P0420 even if your cats are good. Get that leak taken care of, then address the cats. Once you've taken care of that leak, you'll be able to better interpret live data coming from your O2 sensors and figuring out if your cats are actually bad or not.
Happy hunting!
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thaeleelyr
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Jan 16, 2013 05:21 PM