![]() ![]() If it never goes below that, then the test will never run. How hot has it been in your area recently? One of the enable conditions is an ambient temperature of less that 86 degrees, or 30 degrees celsius. Service.gm.com/gmspo/mode6/pdf/2002/2002file4.pdfĭown on page 34 is the criteria for P0440. There's a fantastic PDF on GM monitor enable conditions that you can reference if you're looking at scan data: After sitting overnight, both sensors should read within a few degrees of one another. Mostly I'm interested in checking the ECT and IAT PIDs to make sure they more or less agree. I understand that you don't have a fancy scanner, but do you have access to scan data? Good ol' Global OBD data will work. I'm sure you filled up somewhere in there! I was going to ask about fuel level, as the EVAP monitor will usually only run between 3/4 and 1/4 fuel levels, but then you said you drove it 500 miles. A borderline O2, for example, can stop the whole process. The presence of any EVAP related DTC fault codes will prevent the EVAP System monitor from running.For our information, is the EVAP monitor the only one that hasn't completed, or are there other monitors still incomplete? I ask because some vehicles are very picky about the order in which they run monitors. All of the components in the EVAP control system must also be functioning normally. On some vehicles, the EVAP monitor runs when the vehicle has been cruising on the highway at light throttle at a speed of 45 to 65 mph for at least 10 minutes or more. The vehicle must also have sat overnight or for at least 8 hours without being driven. The ambient outside temperature must not be too hot (above 95 degrees) or too cold (below 30 degrees) because this affects fuel volatility and the amount of vapor inside the tank. Generally speaking, the fuel tank must be 1/4 to 3/4 full because a near empty tank or a full tank can affect the accuracy of the EVAP self-test. The requirements for running the EVAP monitor vary depending on the year, make and model of your vehicle. The PCM will command the check engine light to illuminate and store a DTC if the fault occurs during 2 drive cycles. If the PCM detects no airflow when the EVAP canister purge valve is opened, or it detects a leak that equals or exceeds the amount of air that would pass through a hole 0.040 inches in diameter (0.020 inches for 2000 and up model year vehicles) a pending DTC fault code is stored. The EVAP monitor checks for fuel vapor leaks (including a loose or missing gas cap).ĭuring EVAP system monitoring the PCM tests for vapor leaks by applying vacuum or pressure to the fuel tank, vapor lines and charcoal canister. For 2000 and newer vehicles, the leakage rate has been reduced to the equivalent of a. 040 inches in diameter in a fuel vapor hose or filler cap. For 1996 through 1999 vehicles, the federal standard allows leaks up to the equivalent of a hole. The EVAP system monitor checks for fuel vapor leaks by performing either a pressure or vacuum test on the fuel system. As with most other monitored OBD II systems, all EVAP electrical components are checked for electrical and rationality faults during continuous monitoring. The leak detection portion of the monitor may be activated under normal engine and vehicle operating conditions, during extended idle or soon after the vehicle has been shut off. A portion of the monitor is activated during canister purge operation that occurs under normal engine and vehicle operating conditions. The EVAP system monitor allows the PCM to test the integrity of the fuel system and its ability to draw fuel vapor into the engine for combustion. OBD II Readiness Monitors Non-Continuous Monitors EVAP System Monitor ![]()
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