Vehicle technology has grown by leaps and bounds over the last two decades. One of these huge steps forward has been in how vehicles are able to constantly monitor their own internal systems and alert the driver if there is a fault. That’s where vehicle diagnostic tools (or scanners) comes into play.
Cars and trucks boast a complex series of sensor-powered, on-board “self-care” systems to keep them driving reliably for years. All of these are linked up to a central computer, the ECU, which takes data from sensors and switches, and translates the data into actions, whether that’s decreasing fuel consumption or keeping your brakes from locking up. When there is a fault, the check engine light comes on, the ECM stores a code pointing to the detected problem, and then it intuits the missing data needed to keep the vehicle going as smoothly as possible. The standardized OBD II (On Board Diagnostics) port is the result of a federal mandate ensuring all vehicles manufactured after 1996 are compatible with the same connector. The port is connected to the ECM so that when a scanner is hooked up correctly, it can pull a list of all trouble codes stored within, giving you a good starting point to solve the problem.
How to Scan
OBD II ports are generally located under the dash on the driver’s side. With the key out, plug in the male side of the scan tool. Some scanners get power directly from the car’s own battery, and some power from within, so follow instructions to get your diagnostic tool powered up. Once it’s on and connected, turn the key to the on position but don’t start the engine. Follow the instructions on the diagnostic tool screen to look up codes and where applicable, clear them. You cannot use a scanner to clear codes to pass an emissions test without the problem itself being fixed. To pass inspection, the car has to be driven long enough for the ECU to register no faults as opposed to simply cleared faults.
There are a wide variety of scanners on the market, from less expensive, straightforward code readers to top end models costing in the thousands with all kinds of special features and capabilities. Top end scanners like those used by your local NAPA AutoCare experts can help a trained technician pinpoint a problem in a fraction of the time, making a professional diagnostic fee a wise investment.
Check out all the relays, sensors and switches
Photos courtesy of Bosch Automotive Service Solutions and Blair Lampe.
Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter. In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.