Reset the OBD and drove a couple of hundred miles more, but still was not ready. Tried the emissions a few times and had the same 'Not ready" codes. Drove the car for a few hundred miles in city and it would still not be ready. Whether you’re thinking of reflashing your own powertrain control module or purchasing a replacement, our guide will answer all your questions.Passed Emissions after Catalyst and O2 Not ReadyĢ005 Hyundai Sonata - 4 Cyl - After changing the battery, I had the same problem of the Catalyst and O2 test not ready at the emissions. We’ll help you understand how reflashing works and what your options are, so you can make the right decision for your car and budget. Let’s begin with a brief overview of how car computers evolved, and the role of the powertrain control module in today’s vehicles. The first computers appeared in cars during the late 1960s and early 1970s. Circuit boards had specific roles like regulating fuel injection systems. It wasn’t until the 1980s that microchips and microprocessors became small enough to fit into cars. By the 1990s, on-board computers became more sophisticated. They could now control most of the electrical processes of the car, including climate controls, braking systems, and odometer. Today, vehicles are really like computers with wheels. Cars are upgradeable and customizable, giving the backyard mechanic incredible control over performance. Modern vehicles have a set of computers (commonly referred to as modules) that communicate with sensors throughout the car.
They do this through a system of wires and software protocols called the Controller Area Network, or CAN. Manufacturers started phasing in CANs in the early 2000s.
They’re now standard on all 2008 and newer cars and light trucks. The powertrain control module (PCM) is one of the most important computers in your car, usually managing the engine and transmission, depending on the make of your vehicle. It’s often referred to as the “brain” of your car because it controls so many functions. What’s the Difference Between an ECM, TCM & PCM?īefore we go any further, it’s important to understand the terms that get thrown around in the industry, especially if you’re doing a DIY project or ordering parts online. Sometimes ECM or ECU are used interchangeably with PCM, so let’s clarify the differences. In a modern engine, the ECM will gather sensor data from the intake, exhaust, cooling system, and several internal components to assess the engine’s running condition. Then, the computer can adjust the ignition and fuel injection timing and the position of the camshafts and throttle. The TCM uses incoming sensor data to determine when the transmission needs to shift. TCM functionality has improved over the years, adding input from cruise control, throttle and traction control system. This reduces gear hunting and wheel spin. In most cars, the Powertrain Control Module contains the ECM and TCM in one unit. By combining them, the PCM can better regulate their functions together. For example, when the PCM changes gears, it can pull back the throttle to shift smoother. However, the two units operate independently. You can program one system without affecting the other. To confuse things a bit more, the term electronic control unit (ECU) is often used as a generic term for any built-in system that controls multiple electrical features in a car.