There is no end of Auto parts stores willing to DE-CODE your Check Engine Light fro FREE with a slant toward selling more parts. Many will say "de-code" is "diagnosis". It is not! All vehicles sold in the United States after 1994 were required to have a vehicle information port (OBDII port). This port enables anyone with a device to read trouble codes stored in the computer. This might include the primary computer or ECU(electronic control unit), the BCM(body control module), the TCM(transmission control module), and others. Each of these units can store a multitude of codes. Some codes are related and some are indicating other switches and sensors throughout the electronic control systems. Most are connected to a dash warning light, CEL(check engine light), SES(service engine soon), and in some cases a symbol that resembles an icon or action. Other warning lights in the dash may include SRS(safety restraint system), TCS(traction control system), ABS(anti-lock brake system) and others.
Perhaps this will provide a better understanding of why shops charge separately for diagnosis vs de-coding. Understandably some customers are at odds when it comes to diagnosis charges. Some feel that diagnosis is unwarranted; that we should just find the problem(for free) and charge only for the repair. That would most certainly be the case if the problem were staring us in the face like a flat tire;but rarely is that the case.Most customers understand with computers running everything from can openers to drones that a thorough diagnosis will lead to a complete and proper repair. If we take a video and show the technician working on a problem, pin testing connectors, viewing information on the scan tool, more pin testing, checking under the hood or the dash, then observing a DVOM(digital volt/ohm meter) and running more tests based on the codes that were retrieved when the de-code was performed, I think most watching might have a better appreciation for the amount of involvement and time needed to reach the proper diagnosis. Many problems are identified within the first hour of time spent on the vehicle. For example: rodents chewing thru wires is becoming more frequent due to peanut oil being used in the production of auto wiring. Often electrical/electronic system issues are more difficult to locate and thus require more time. The skill level of the technician cannot be understated in finding issues in the least amount of time. In some instances, when the problem is found, it requires replacement of a component such as a switch, sensor, or module. These can often be hidden in the interior of the vehicle,or inside the transmission, or engine. Often replacement of a part means the system will need to be reprogrammed. This is something the customer may be unaware of when it comes to charges, especially when sorting out information from misinformed sources. I find it interesting when a customer says: "I have a friend who knows all about cars and they said....." Understandably customers want to be helpful. We are always interested in information that may lead us to a solution quickly, however once you have committed your car to a shop that you trust, please give them the benefit of the doubt when they advise you on what it will take to fix your car.
Most highly skilled shops are dedicated to their trade and deeply concerned about the customer and their vehicle. We are one of those shops.
Keep the wheels turning. tp