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Guest
Anonymous Poster
casperceo@hotmail.com
Jun 6, 2006, 2:04 PM
Post #1 of 4
(1968 views)
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Help with Screwy Repair
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I am having a problem with my emission test on a 2003 Volkswagen Jetta. I recently had my check engine light on, and failed emissions because of it. In trying to get it repaired, I was told that the O2 sensor was faulty, and over $400 later, it was suppose to be fixed. Four days later the check engine light is back on. I returned to the place of repair and they said that now code 420 is showing and that the catalyst system either needs to be cleaned or completely repaired, which would require another test to be run, and then repair of who knows what $ amount. Wouldn't the first initial testing have shown this? What are the chances that 4 days later a whole new emissions problem would be present that was caught the first go around? I feel like I'm being screwed with. What is your advice?
Thanks
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 6, 2006, 11:12 PM
Post #2 of 4
(1965 views)
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Re: Help with Screwy Repair
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A 2003!! How many miles do you have on it? Isn't a warranty still in effect? Codes don't clear and some emissions tests will pick up on it and fail you if you even just swapped a battery. If running well I'd just drive it and give it a chance. If not get it fixed. I think most cars reset withing a couple hundred miles or so many starts. Good luck, T
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carjunky
Enthusiast
Jun 7, 2006, 6:32 AM
Post #3 of 4
(1964 views)
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Re: Help with Screwy Repair
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Some other things to consider.... gasoline you are using.... do you drive using regular and the car recommends premium... Also did you drive the car for at least 20 minutes prior to being tested.... A car needs to be warmed up before the catalytic system really begins to work well.... Also do you drive any highway miles or all local roads.... some times cars need to be "Driven " a little to clean themselves out...
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DanD
Veteran
/ Moderator
Jun 7, 2006, 11:00 AM
Post #4 of 4
(1958 views)
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Re: Help with Screwy Repair
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There’s a possibility that now with all the O2’s functioning properly the computer is capable of running an efficiency test on the converter????
There are pre and post converter O2 sensors that the computer uses signals from both to calculate converter efficiency, so with one O2 not functioning the computer cannot perform the test so how can it set a low efficiency code.
So they probably have performed the proper repair for the O2 but now the computer can pick up the converted that may have failed due to some form of contamination. Probably the same thing that took out the O2.
What you need to do is have your repair facility do there own efficiency test on the converter and stop guessing on whether the converter is bad or not. It’s an easy test if they have a gas analyzer.
Drill a test port in the exhaust pipe in front of the converter that can be easily plugged afterwards. Take a gas reading of HC, CO and NOX; at this port/hole then plug the port. Now take a reading at the tail pipe of the same three gases at the same rpm and engine temperature.
Here’s the formula to calculate the percentage of efficiency.
Per converter reading, subtract post reading, divide by pre then multiplied by 100 = percentage of efficiency. Use the same formula for all three gases; if any one of the gases show below 70%; you can consider the converter to be on its last legs.
I’ve had some success running combustion chamber cleaner through the engine to being back a converter; maybe a one in ten chance.
Dan.
Canadian "EH"
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