Before you buy a used vehicle or if you need assistance in diagnosing an (automotive) electrical or computer problem please contact us. A $900 mistake...
An acquaintance of mine recently purchased a used vehicle. He knew enough to check to see if any warning lights on the dashboard were on. He took the car for state inspection. The car failed for several reasons. One of which was because the Check Engine warning light was not working. It also failed because there was a Diagnostic Trouble Code (DTC) stored in the computer. I checked the car for him and found that the bulb for the Check Engine light had been removed from the back of the speedometer (instrument cluster). We assumed that the seller of the car purposely removed the bulb so that potential buyers would not see that the Check Engine light was on. The Diagnostic Trouble Code (DTC) stored in the cars' computer was P0420 which indicated that the car had a bad catalytic converter. $900 later the car was fixed and passed state inspection. If you are looking to buy a used car we can help you make sure it's a good one. It takes the proper tools and expertise to thoroughly check a car for existing and obvious problems as well as pending, potential and/or hidden problems. Most people know an illuminated Check Engine light is an indication of an existing problem. What you may not know is that most vehicles have computer systems which store data not only about existing "hard" failures but also about pending "soft" failures. Using the appropriate diagnostic equipment this stored data can be retrieved, viewed and diagnosed. Such equipment (commonly called a scanner) can be purchased by anyone but is quite expensive. These types of scanners typically cost between $3000 and $15,000. It is important that you understand a little bit about automotive computer diagnostics. To begin, let me explain what a DTC is. DTCs (Diagnostic Failure Codes) contain 1 letter followed by 4 numbers. For example P1000 or B2500, etc. Trained, professional technicians, using the appropriate diagnostic tool, connected to the vehicle, can retrieve DTCs. There are literally hundreds of DTCs. Each DTC corresponds to a specific failure. Here are a few examples:
P0100 Mass or Volume Air Flow Circuit Malfunction
P0118 Engine Coolant Temperature Circuit High Input
P0267 Cylinder 3 Injector Circuit Low
P0303 Cylinder 3 Misfire
There are also different types of DTCs. "P" type codes (P # # ) relate to engine/transmission type failures. There are also "B", "C", "U" DTCs (Body, Chassis, Network). Different type codes are stored in different computer modules. Each module must be "scanned" with appropriate diagnostic equipment to check for stored DTCs. DTCs can be "hard - current" failures or "soft - pending" failures. Most, but not all, hard codes will illuminate a warning light on the dashboard (instrument cluster). Soft codes generally will not turn on warning lights. To properly check a vehicle technicians MUST check each computer module for both current AND pending DTCs. For around $75 you can purchase a "code reader" which have extremely limited capabilities. Code readers are able to check a car for existing, current "P" type DTCs and can clear/erase them. The problem is that with the same $75 tool the seller of the car can clear (erase) any DTCs. Doing so would also temporarily turn off the check engine light. A typical person would never know. Our scanners can check to see if DTCs have been recently erased/cleared. We can check to see if the tests that the cars' computer performs have actually been performed, or not. If any DTCs have been recently erased it could take days and hundreds of miles of driving before the cars' computer performs all required tests and the DTC returns. We can check for this type of situation. It is actually called "Ready Status". When DTCs are cleared/erased all tests that the computer performs are in what is called a "Not Ready" status (which, by the way, will cause the vehicle to fail state inspection). Once a test is performed the test status changes to "Ready". If a test fails a DTC will get stored and the Check Engine light will be illuminated. Our tools can check the "Status" of all required tests. We can also check for pending codes. Pending DTCs (diagnostic trouble codes) are "soft" failures, meaning that the car's computer saw a problem but for some reason the problem was not severe enough to turn on the Check Engine light. An example could be the computer saw a problem occur once but for the computer to illuminate the check engine light the problem must occur 3 times. The lesson here is obvious. Before you hand over thousands of dollars to buy a used vehicle have it checked - properly. Cars, these days, have many computers and modules such as Engine Control, Powertrain, Transmission, Anti-Lock Brakes, Air Bags, Suspension Control, Entertainment, Network, Comfort Control and more. These computers and modules have the ability to alert you to what could amount to very expensive repairs.
