Welcome to the Mid-City Auto Service site!

We are equipped to do factory programming/re-flashing on Ford and General Motors vehicles!

Specialties include: Electrical Systems -- Computer Diagnostics -- Brakes -- "Tune Up"-- Internal Engine Repair -- Clutches -- Differential -- Cooling System -- Air Conditioning/Heating Systems -- Routine Maintenance -- CV & U Joints

Service/Check Engine Light Specialists! Cadillac Northstar Specialists! Corvette Specialists! Ford PowerStroke Diesel Specialists!

Service Engine Light

The Check Engine Light


As you may or may not be aware, there are parts supply stores that will plug a device into your car and read your computer’s fault code and this will tell you exactly what part needs to be replaced, which will save you a ton of money versus taking it to a shop….and they will be happy to sell you the part….imagine that huh?Do not fall victim to this…This is NOT how faults are diagnosed, that fault code the scanner retrieved is only a TOOL…often…VERY OFTEN, the part they sell you is not the real problem and is NOT NEEDED.

There is more to the story…

Picture this…your service engine soon light is coming on…or your vehicle is just not running right so you whip on into one of the parts stores that offers this service…the dude walks out to your car, plugs in this little gizmo and tells you confidently that all you need is an oxygen sensor. Ten minutes later you are on your way with your oxygen sensor…this dude is your hero….he diagnosed your car for free….the shops all wanted anywhere from $60 on up to do it….and he sold you the sensor for a lot less than ANY shop you called! KEEYAAW life is good….. Well you finally found the time to change that oxygen sensor, or have your buddy or relative do it for you….you saved a hunk of money on the part and it only cost you a six pack of beer and that one little part he accidentally broke for the labor….man it just doesn’t get any better than this right…..Well here you are a few days later driving down the street and your service engine soon light comes back on…or your vehicle starts running bad again…so you whip on in to see your hero again….he walks out there with his gizmo, plugs it in and proudly announces you need an oxygen sensor…hmmmm….you just did that….hmmmm….you tell him you just did that and ask him what could be the problem…he tells you he has no clue…he’s not a mechanic…you need to bring it to a shop! OR WORSE! He may try to sell you ANOTHER part you do not need!Now you have dropped your vehicle off at…..let’s use Mid-City 
Auto Service for example….A while later you get the phone call that you have been waiting for….they say they have good news and bad news….here it comes you think….they are gonna try to yank my eyeballs out…..they inform you the good news is they can fix your car for about $65.00 including diagnostic time, parts and labor…..COOL, what is the bad news you ask…..well the bad news is that your problem is a vacuum leak in a deteriorated hose, that is causing the oxygen sensor code….you did not even NEED a new oxygen sensor….the news gets worse…..even if the oxygen sensor would have been the problem, YOU CHANGED THE WRONG ONE ANYWAY…..the one the code pertains to is on the other side of the engine!!!! Guy at the parts store still your hero???? This is not a once-in-a-while occurrence…This happens VERY, VERY OFTEN!!!!

Well boys and girls, here is the real deal….the code reader is exactly that…it reads the code. It cannot let the user look at the data of the many sensors in the system and even if it did show this info like a full fledged scan tool, it takes much training and years of experience to interpret this info correctly. 

A common misconception is that the fault code displayed by the code reader or scan tool tells you the problem with the car…WRONG, WRONG, WRONG!…this is just the first piece of the puzzle.  We must enter that fault into our diagnostic service information, and it may print out 5 pages of step by step tests we must perform to find the REAL source of the problem. The code scanner is simply a tool, no different than a screwdriver or wrench, it is NOT a magic diagnostic machine. 

For example if the code was bank 1 oxygen sensor 1 lean…you must first know which oxygen sensor is bank 1 sensor 1….some vehicles have as many as 6 oxygen sensors! The next step is to pull up the diagnostic procedure in the service manual for this particular code. This procedure can be as long as 5 pages or MORE of small print, involving 50 or MORE steps to confirm the needed repair. You see it is not as simple as plugging in a magic gizmo and it telling you the problem. Case in point…in the above scenario the oxygen sensor fault code can be caused by something as simple as a vacuum hose that has split and fallen off causing a small vacuum leak.

 A defective spark plug wire can even cause an oxygen sensor code! The sensor is just that…it senses oxygen in the exhaust stream…if there is a defective spark plug wire causing one cylinder to misfire, the fuel is not burning in this cylinder…if the fuel is not burning then neither is the oxygen, causing an over abundance of oxygen…therefore setting a FALSE oxygen sensor lean code!

I’ve heard in some cities that some parts stores that used to provide this free service are no longer doing so due to lawsuits stemming from selling expensive parts that were not needed. JUST LIKE in the example I gave above!!
The story goes this way…You see If the EGR valve passages are clogged with carbon there will be an EGR insufficient flow code set….the parts stores were not experienced enough to know this and were telling customers they needed an EGR valve….some of these valves are VERY expensive and naturally after spending all this money the car was NOT fixed….Then after taking the car to an experienced technician they would find out the expensive EGR valve was not even needed!!

If you do not know all of this and you simply change the part the fault code refers to you WILL still have the same problem 99% of the time….

So you see the dude at the parts store with the code reader gizmo is no hero…he is just one of the many pawns in the parts selling game!

Many inexperienced shops are doing this type of work as well and are replacing many parts that do not need to be replaced before finally stumbling upon the REAL problem! 
Problems in these systems can cause other “false” problems that will correct themselves when the ROOT CAUSE of the problem is fixed!

There have been many times we have had cars come in and the customer has spent a lot of money on his own or even at another shop and their vehicle is still not fixed, only to find had the other shop been experienced enough, the problem could have been fixed for a lot less money.
This happens VERY OFTEN…I’d say three or four times a month!

Let me tell you a little story that took place about 15 or 20 years ago when I was still prone to showing off…
I was asked by a counterman at one of the parts stores I dealt with if I would mind helping another shop diagnose a Ford pick-up they were having trouble with…You see this was a shop that had moved to a new bigger location not long before and did not have much experience in this…they mostly did light maintenance, tires, front end stuff, brakes etc. but were trying to expand on the repairs they did. I said sure, no problem. Well the manager of this place called me and explained what was going on and went on to tell me that they had replaced the ignition module, distributor pick up, ignition coil, ECM, ECM power relay and fuel pump relay…all in attempt to get this truck to start. Well I asked him a few questions and he put his tech on the phone and I told him to make sure the ground wire leaving the negative battery terminal was good, explaining that the connector about 6 inches down in the wire was bad about building up corrosion and that this was the ground for the ECM. I tried to explain to him how to do a voltage-drop test on this ground circuit, but he had no meter and couldn’t grasp what I was saying anyway so I finally just told him how to use a test light hooked to battery positive to test this ground. Well later that day the manager called back and asked if I would mind going to look at the truck at this other shop as they had not had any luck getting it to run…naturally I said yes even though this place was on the other side of town from me and I already had all I could do that day, cause like I said, back then I liked nothing better than to show off …

Well anyway, back to the story…I get to this shop and walk over to the truck and ask the guy working on it if he checked the ground I asked him to…he said yes it is good. I then asked him to try to start it as I watched for spark and fuel pressure…There was neither, so I asked him for some wire cutters, and I proceeded to cut the connector out of the wire I had mentioned and then tied the two wires together…I told him to try it then and poof, the truck started….well that manager of that shop jumped a foot high and started screaming and hollering how they had spent 800-900 dollars on JUST PARTS for this truck and had worked on it for three days, and it could have been fixed in 15 minutes for just a few bucks!

Well later on I was talking to a good friend of mine telling him how it was a low down dirty shame that this customer was going to have well over a thousand dollar bill for something that would have only cost them a few bucks at my shop, when all of a sudden my friend looks at me and says “yea…the guy had a huge bill, but all he knows is that he took his truck there and it cost a lot of money but they fixed the problem…He will probably go back to that shop too, because all he knows is they fixed his truck, but guess what

Tony…You fixed it for FREE and they got all his money” 

Well right then is when I decided that was the end of my showing off!

This same shop took many of their customer’s vehicles to us to diagnose for  them after that. We would DIAGNOSE them and charge them for the diagnosis, then they would pick up the vehicle and take it back to their shop to do whatever repair we told them it needed, unbeknownst to their customer…but they always wanted me to drop what I was doing to work on their stuff…All the while WE were getting behind on OUR customers cars! Finally I wised up and just started telling them that we didn’t have time to diagnose their cars for them any longer…