P0442 - Evaporative Emission Control System Leak Detected (small leak)
P0456 - EVAP Leak Monitor Small Leak Detected
Both codes mean the same thing. You need the smoke machine to find the cause because there's dozens of places to look. It sounds like the first mechanic diagnosed the cause already, but you want to complicate the issue a bunch. I can't fault you for trying to save money, but what you're proposing is like buying groceries from a grocery store, taking them to a restaurant, and asking them to let your friend use their kitchen to cook a meal for you, in an attempt to save money.
Unless you know for sure the diagnosis is correct or you saw where the smoke was coming out yourself, it could be wrong or incomplete. You're going to buy a part, but what happens if that part is defective? What if the installer breaks the part or does something else wrong?
What if there's two or three leaks and the new parts don't solve the returning fault codes? You have to consider dry-rotted rubber hoses, lose hose clamps, leaking rubber o-rings and seals on the fuel pump assembly, filler tube, purge valve, charcoal canister, etc. Some leaks can be so small that they don't get detected right away. You may not see them right away with the smoke machine. Also, more than one of us has been fooled into overlooking a second or third leak after we find the first one and stop looking. Some leaks are big enough that the smoke comes out easily and can be seen, but no pressure can build up because of that, so no smoke comes out of other leaks. That's why it's common to fix one leak, then find another one after that repair is done and the system is rechecked.
I shuddered when I read that you want to hand a part to a friend and have him change it. Who are you going to blame or hold responsible if the fault code comes right back? To that friend, that's like a restauranteur ordering a meal from a competitor and serving it to you. Who gets blamed if it doesn't taste good or isn't prepared properly?
I know this isn't what you asked, but you're trying to add a lot of unnecessary variables and complicating factors to what sounds like a straight-forward, easy repair. What is your friend going to do if the code comes right back? He didn't have the chance to diagnose it for himself. He's just going on the word of some other mechanic and you, but he deserves to be paid for his time. He's your friend, but he's still a professional. No other professional works for free. You've got one person diagnosing, one buying parts, and one installing them. You'll have to weigh the risk of something going wrong or someone being angry against the few dollars you might save.
I don't like to tell you where to spend your money, but if the first mechanic knows of your plans, he has no interest in looking for additional problems when he knows he won't be on the hook for a misdiagnosis. I hope this isn't the case, but he could also intentionally provide a misleading diagnosis to cause grief for your friend, or to "punish" you for cutting him out of the picture. Most of us wouldn't do that, but there are people in every profession who will. Some people are so lacking in confidence in their own abilities that they resort to making other people look bad in a misguided attempt at making themselves look better.
If you don't trust the first guy, that's a different story. You haven't said anything to suggest that, but if that's the case, you're better off getting a second opinion from a different shop, or allow your friend to diagnose the cause of the problem himself and do the complete job. Then, it's up to the two of you who buys the parts and what happens if the job has to be done a second time.
When a shop buys a part, they mark it up a little just like every other business. That profit goes toward the business' cost in ordering and getting the part to the shop, and doing that a second time when the wrong one got delivered. Depending on what your time is worth and how far you have to drive, you may spend more in time and gas than that little profit the shop makes. It's pretty common to get defective new parts, and no one likes to admit it, but we do break parts sometimes. No one would expect to charge you for a second part if we break the first one. That profit helps cover those costs and it's why shop owners don't get too excited when an employee breaks something. That isn't the case when you provide your own parts. If one is defective, you can be expected to supply the second one and to pay for the labor to replace it a second time. If you simply got the wrong part, you'll have to walk to the parts store with that one to exchange it while your vehicle is sitting on the hoist, torn apart. That makes that shop bay unusable for other customers' service needs.
As a final thought, you have to keep in mind that professional mechanics in repair shops rarely fix things. We diagnose problems and replace things. This is especially true in new-car dealerships with cars under warranty. I worked for a very nice family-owned Chrysler dealership through all of the '90s, and in that time I "repaired" two power antennas. One had a curve to it from going through a car wash. I used my experience with installing and repairing tv antennas to straighten the antenna without kinking it. The second one simply was coated with bug juice. Cleaning it took care of the problem. In both cases they were under warranty, and Chrysler insisted I replace the complete assemblies even though the owners were happy. That was because that was the only way CHRYSLER knew and could guarantee the problems were solved.
My reason for sharing that sad story is there may be a way to repair something on your vehicle that doesn't involve buying parts. The first mechanic would have to be confident in his ability to do that repair, and that it would last, and that his boss would approve of it. This is where repeat problems get tricky. If you come back with the same problem, (even if it's a leak in a different place), you're going to expect it to be fixed at no additional charge. Most of the time shop owners feel obligated to pay the mechanic's time for the second attempt, but they don't charge you. Shop owners want to save you money too, but they know it's better for everyone in the long run to do it right the first time. If "doing it right" means replacing a part that might be fixable, that's what they're going to do. They know you'll forget about the dollars pretty quickly, but you'll remember the inconvenience of making a second return trip every time someone asks for a recommendation of a good shop. That's not the cased with your friend. He may be able to fix the problem, but then it's up to him to do the job over if that becomes necessary. If you trust him enough to do the work, I'd let him come up with his own diagnosis and plan of repair. Many auto parts stores rent or borrow tools and they should have a smoke machine.
Saturday, September 13th, 2014 AT 7:13 PM