Year after year, state inspection/maintenance (I/M) administrators across the country report P0171 as one of the top ten DTCs that are set. Here is a more detailed list of the most common causes when your engine running rich. The system will enter the diagnostic mode. You mentioned the Check Engine Light is on - getting the problem codes is task #1. Having stored or even pending diagnostic trouble codes active may prevent a monitor from running to completion. Lean codes and lean-running conditions are a widespread problem that you’ll likely see again and again, on all makes and models. These are a few of the more common engine codes on many vehicles, but remember that making the right call on diagnosis and troubleshooting can often require an experienced tech. I have a 1986 Honda Accord lxi, The pgm-fi light is coming on periodically. Some monitors, for instance the EVAP monitor, may require the fuel level to be between 35% and 85% to initiate the diagnostic testing. 1. It still runs fine most of the time. If he just cleared the codes its normal for the engine to run different. The Vehicle speed sensor. Hi there - a car that sputters may have an ignition misfire, or a fuel supply issue causing this behavior. This computer will make adjustments to your vehicle’s performance to keep your ride running smoothly. My problem is finding out where on the car that part is located. I checked the code from under the driver seat, and it is a #17. Second, make sure that you have enough fuel in the car. No need buying a scanner or running to any parts stores to check the engine light. Thus, a P0302 misfire code on a Nissan means the same thing on a Honda, Toyota or Mercedes-Benz. The most common causes when an engine running rich are check engine light, black smoke from the exhaust, high fuel consumption, poor engine performance, and sooty spark plugs. Since the 1980s, many vehicles have been built to be run by the engine computer unit (ECU), which controls vehicle’s drivetrain and auxiliary systems based on input from the vehicle’s sensors. A recent iATN search for the two most common lean codes, P0171 […] Put your key in the ignition and switch the vehicle to “on.” Do not start the vehicle. Drive your vehicle to your regular shop and have them re-check your readiness monitors, present codes, and pending codes. Then, press the “read” button on the scanner to access the check engine light code. In this mode, the computer will display a Code 12, three consecutive times, by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" or light. How to read the codes. Vehicles older than 1995 models typically feature the OBD-1 trouble-code system; cars made after 1995 usually have the OBD-2 system. I just want to replace it because I have to smog the car … The code … Ground terminals A and B (see diagram below) with the ignition "ON" and engine not running. 1. The diagnostic codes that are required by law on all OBD II systems are "generic" in the sense that all vehicle manufacturers use the same common code list and the same 16-pin diagnostic connector. This system is called obd1 and applies to most vehicles made before 1995 for domestics and 1993 on imports. Check engine light 2) How to Check the Engine Light Codes for car and trucks made on and before 1995. The differences between the two systems are that the older codes contain two digits, while the new codes begin with a letter indicating what system in the engine is malfunctioning, followed by a series of numbers (see Resources). They should do this as a courtesy and for free. Once the lights on the dash come on, turn off all the vehicle’s accessories, like the radio. When your car had a problem the computer adjusted some parameters so it will run good.When he reset the codes the engine will start running normally but if if it still senses a problem it will revert back to where it was. A worn or carbon-fouled O2 sensor will trigger these engine codes, and one of these codes along with a random misfire code can point to a vacuum leak on the engine.