Ask Pete

[#1]

A vehicle ‘inspection’ is not the same as a ‘diagnosis,’ and a ‘code reader’ diagnosis is not the same as a ‘comprehensive’ diagnosis.

For many years now, AAA has offered members a free 24-Point Vehicle Maintenance Inspection at all AAA Approved Auto Repair facilities in the southern region of The Auto Club Group. This inspection focuses on the parts most frequently responsible for roadside breakdowns. Belts, hoses and tires that are damaged or worn out are the reason behind the vast majority of our road service calls, so it just makes sense to take a proactive approach and inspect these items before they give you problems on the road.

In some cases, folks have mistaken this ‘inspection’ for a ‘diagnosis.’ The 24-Point Inspection is not a diagnosis because it doesn’t involve specialized diagnostic equipment. The inspection is done visually, and if a potential problem is identified and further diagnosis is warranted, the shop will discuss this with the member before going further. Oftentimes, folks whose ‘check engine’ light is on are under the impression that the 24-Point Inspection will determine the cause of the light, only to be disappointed when they learn that it requires a diagnosis and, in most cases, an accompanying diagnostic fee.

I frequently encounter these misunderstandings when I am talking with a member about a ‘check engine’ light that is on, and they end the conversation with, “I’ll go to the parts store. They’ll diagnose it for free.”

Okay, but that’s only partially true! Yes, you can go to the parts store, and yes, they hook up a code reader to your vehicle, and yes, it does have the ability to pull and erase a diagnostic trouble code. But what the code reader can’t do is read the data stream, which is critical for an accurate diagnosis. Pulling a diagnostic trouble code is great for giving a technician direction on where to start looking. But oftentimes, the trouble code is only an indicator of the part that is either the cause or the effect of the problem.

For example, I recently talked with a member who had a parts store tell her the P-0401 code (EGR insufficient flow) that came up on the code reader indicated a bad EGR valve, and they would be happy to sell her a new one for $300. After all was said and done, the valve simply had a clogged vacuum port. The restriction was cleared, the code was erased, and after two weeks of driving, the code never came back—and the vehicle’s fuel economy increased by 20%. In this case, a $300 valve certainly would have fixed the problem, but it would have been the more expensive route to take because it’s cheaper to clean the valve’s clogged port than to replace the valve altogether.   

So here’s the bottom line: In the long run, you will almost always save money if you pay a little for a comprehensive diagnosis and fix a repairable problem than if you get a ‘free’ code reader diagnosis and replace parts unnecessarily.

[#2]

Thanks for this article.  It is so frustrating to me that certain parts stores misrepresent "reading codes" as actually fixing a car.  Technicians go through pretty intensive training learing how to troubleshoot todays very complicated vehicles.  The thought that they can be replaced by a minimum wage retail worker with a code reader is absurd.  Good article.

[#3]

Very good article. Thanks for your insights!

[#4]

Too bad that I paid AAA Auto Care Plus $47.5 to inspect my check engine light, got a quote of almost $1000 for replacing thermostat, coolant temprature sensor, spark plugs, and brake pads, bought the parts myself for less than half of the quoted price and installed them, but only to find that the probelm still exsits. I gave AAA a shot because of the brand but was very dissappointed.

[#5]

Without knowing more about the symptoms, trouble codes, etc it is tough to comment on the diagnosis. If the diagnosis is truly off I'm sure the fee will be refunded. As far as the estimated costs and what you did the repairs yourself for there is no comparison.

[#6]

Hey Pete,

I have a question. I have a 07 Jeep Patriot 4x4 that makes quite a bit of unusual noise under the hood. A friend had suggested that maybe the power steering pump was going bad even though that didn't seem to make too much sense seeing it is a 07 model with 95000 miles. I took it in to get checked at a pep boys and they told me the lower idler arm pulley was shot and so I had them replace it as well as the top idler arm. The service writer also mentioned something about it sounding something like how diesel engines normaly run.  The same service writer had also suggested changing the alternator pully but I decided that I wanted to get a second opinon.  The noise comes from the top of the engine pulleys and since the power steering pump is the first one, I went ahead and replaced that.  I am little hesiant about going to the dealership right away but then I don't want to prolong it too much as I do not have a idea of what might be possibly going out.  I haven't had any real major issues up until this point.   Any advice and or comments?

 Thanks

[#7]

With that much audible noise  suggest getting the looked at by a qualified professional that can stick by their diagnosis. I'd hate to see you keep putting parts on this vehicle without a formal confirmation of defect. There are a few things it could be from a bad idler bearing to a bad water pump and anything in between. The best way to know for sure is to have a qualified technician formally inspect and diagnose your vehicle.  

[#8]

My neighbor told me there is motor oil in the water tank.  How bad is this problem?  Could it be fixed?

[#9]

Oil in the water or vice-versa is never a good thing. On most vehicles today it is usually caused by a bad intake Plenum or manifold gasket. Worse case is a bad cylinder head gasket. While neither repair is inexpensive, they both can have their complexities. The best way to know for sure is to have a qualified technician formally inspect and diagnose your concern.

[#10]

Morning, I am having valve cover gaskets replaced on my 93' e-250 w 232000 mi this morning I will also have plugs and wires done just because I dont know when they were replaced last and with consideration of diffuculty to access through dog box it seems good idea. The only other noticeable issue I have is a slow shift into high gear which with mileage I assume may be the well worn tranny in this workhorse 351ci. van. Any advice on the matter or of anything else reccommended while accessing motor today