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My car needs a "smoke test"...

edited February 2012 in Repair and Maintenance
First off, let me just say that I know absolutely nothing about cars. So feel free to speak to me like an idiot.

Moving on, I drive a 2004 Crown Vic with almost 92,000 miles on it. I recently purchased it from a private seller around a month ago. The Check Engine light came on just today, so I went to a local service center where they told me there's something wrong with the fuel tank (either the pressure or the voltage? I feel like an idiot for forgetting exactly what he said, and he didn't put it on the invoice.. just that my car would need a "smoke test"). Now, they're going to charge around $95 for the smoke test (minus the $45 for the check engine diagnostic they did)... he was a little vague on what the cost would be for the repair (I guessed because he was unsure about what the problem exactly was). What do you think am I looking at price-wise? And do you think it'd be safe for me to continue driving it until I can get it fixed? (He couldn't do the test/repair regardless until Monday.)

Thank you so much for your time in reading. I greatly appreciate any and all responses.


  • edited February 2012
    The problem is related to your fuel tank venting and purging..Sometimes it's just a loose or defective gas cap..If you do not need an emissions TEST then this is not a serious issue that effects the safety or performance of your car..Your car is drivable.
  • No, he said the engine light's code definitely had something to do with the fuel tank, and that the smoke test was required... that is, if I wanted the check engine light to go away and be sure nothing is wrong.
  • edited February 2012
    Did they write the exact error code on the invoice? (Would look like "P1234" - I'm taking a wild guess that yours is P0442).

    The only thing that would bring on a smoke test is exactly what Caddyman said - an issue having to do with fuel tank venting. Fuel evaporates - creates a lot of fumes. Today's car's keep the fumes in an "evaporative emissions system." Its a series of tubes that capture the fumes from the tank and send them to a canister in the front of the car, and then send them to the engine to be burned.

    In other words, your fuel system is supposed to be totally closed to the atmosphere. The car "tests" it once in a while to see if its closed. If the series of evap tubes won't hold a vacuum then it will set an error code because there is a leak someplace. A small leak code is P0442.

    The hard part is finding the small leak - thus a smoke test.

    However, one of the most common reasons a P0442 gets set is because of a gas cap that doesn't deal completely - as Caddyman said.
  • I've twisted that thing so tight that I don't think it could be responsible, but then again, maybe it is... I mean, it doesn't "click" like it says it should ("Twist cap until it clicks or check engine light may turn on" is right on the cap), so I have to go based on my own strength—thus, when I can't twist it any further, I declare it sealed. Is this something that they would normally check or should I bring it up when I go back Monday afternoon? Further, should I do anything myself or ask any particular questions? I was considering calling them back before the night's over, but I'm not so sure what on earth to ask. I mean, I want to get a solid price on what the repair would be.

    No, he didn't state the error code on the invoice. I found that odd, but then again I could have asked many more questions than I did there. Even if there is a leak, though, the car will be fine to drive until it's fixed?
  • edited February 2012
    Thanks Cig. On a Vic, the EVAP canister and much of the plumbing are mounted on the center of the trunk well, under the car, easy to inspect for damage...It's not a safety issue..You can slide under the back of your car, look up at the bottom of the trunk and there it is. You can reset the dash light by disconnecting a battery cable for 30 seconds..But this will erase any stored trouble codes...Any parts store will read the codes for you for free...Then post the code back here...
  • edited February 2012
    I called the mechanic and he told me it wasn't the EVAP code, it was an FTP sensor reporting an irregular voltage... He didn't say there was a code, however.

    EDIT: Basically, he's not telling me a figure about what the cost will be, so I wanted to know a ballpark figure of what I could be looking at... second, I was wondering if it were safe to drive.
  • The mechanic can't tell you what it's going to cost until the smoke test shows results. That is why he is hesitant to provide an additional estimate. Get the test done and have him call you to discuss results and costs.

    I think we all agree it is safe to drive until you have the smoke test done, or if you choose the get the codes read free at a participating auto store and post back here to see if anyone has any additional info or guidance.
  • I think you should have the test done and the repair made soon. You never know when the CEL will come on and it will be a more serious issue if you don't have this one fixed.
  • 369, you are being set up for a four figure repair bill when there is nothing of any importance wrong with your car...If there is something seriously wrong with your car, you will know about it without the CEL complaining about some emissions problem, real or imaginary...

    "It uses this sensor, also known as a fuel tank pressure (FTP) sensor to check for leaks. Basically P0453 means the PCM (Powertrain Control Module) noticed the EVAP Pressure sensor or FTP is indicating a higher than normal pressure (above 4.5 Volts) in the EVAP system. NOTE: On some vehicles the FTP is a part of the fuel pump assembly in the tank."

  • Ask them to explain how a smoke test is going to help - because I doubt that it will. But if you report the specific code people could say more. If it is P0453, as Caddyman suggests, then the first thing to check is the sensor's wiring.

    IF, in fact, there is an actual evap system problem, it will be a system blockage - not a leak. In a smoke test you just pump smoke into the lines and look for where it escapes. If there's a blockage, there will be no escape.

    What kind of a shop did you bring it to.

This discussion has been closed.