EVAP Test Smog Check Questions & Answers

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Question: I have a 1994 Volvo. Did not pass the emissions test due to failed fuel evaporative controls functional test. What does this mean? How much would it cost for me to fix this problem? Can I take my car to just any smog repair station? Is it difficult to diagnose the problem? I don't want to pay for the repair and not have the vehicle pass on a 2nd try. I did pass 2 out of the 3 smog requirements.

 

Answer: The EVAP Functional Test (LPFET) is in addition to the smog check test. All 1976 to 1995 model year vehicles will be tested, which includes all pre OBDII vehicles subject to Smog Check. The most important impact on consumers is that the emission reductions will improve air quality and reduce their health risks. This test is designed to ensure your vehicle's fuel evaporative system is not leaking gas fumes in to the atmosphere. It is estimated that over 7,000,000 vehicles will need to be tested each year and of those 11% will fail. The average cost to repair a failed EVAP system is estimated to be approximately $250.00.

 

Question: My 1999 Dodge Stratus passed smog when it was owned by someone else.  After I bought it, it was repaired and both the fuel and water pumps and most of the fuel system was replaced and a recall repair made on the shift, involving drilling of the shift lever dimple and installing a rod.  Immediately the next day the check engine light went on and it will not pass smog. The place that repaired the car says it is the leak detection pump and no fault of theirs. Someone else who ran diagnostics as a favor says it is a leak sensor and I have been able to actually hear the hiss of a leak myself. The repair shop now wants almost $500 to replace the leak detection pump so the car can pass smog. However, I have learned that kinks and the like  in the supply vacuum lines can cause gross mis-diagnosis, especially in this vehicle including low flow purge errors. I am wondering if they are responsible for kinking the lines up during the repairs to the fuel system, since the lines run all the way from the engine compartment to the fuel tank.  Shouldn't they have checked the lines before giving the car back to me? The repair manager is telling me all this is just a coincidence. I need someone to give me an honest opinion.

 

Answer: Since you've had the vehicle diagnosed and the problem is apparently a faulty leak sensor we would assume making this repair will correct the Check Engine light problem. At this point there is no mention from the station which did the diagnosis about kinks in the lines. if in fact you've read about kinks and this being a common problem, you may want to have a station do a diagnosis to ensure there are no kinks in the system, before replacing the leak sensor/system. I assume the station which has determined the sensor to be the fault has checked for kinks, but I recommend confirming with them again. If there are kinks, determining whose fault it is will require to look into exactly which parts of the fuel system were worked on originally and if the kinks are in the area where work was done.

 

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Question: Good afternoon, i was wondering if a P0442 EVAP ctrl system small leak is detected, will this fail my car in a california smog check?

 

Answer: Yes, the EVAP system is an emissions control system monitored by your vehicle's emissions computer. Failure of this system or any component within the system is an automatic smog check failure. Vehicle manufacturers have placed the Check Engine light inside the passenger compartment to inform the driver there has been or is an engine or drive train malfunction. Very often you may not notice an engine problem, but this is only because your engine's computer is operating under pre-programmed information rather then of real-time. In other words the problem still exists but your engine learns to live with it. To avoid spending hundreds down the road, the Check Engine light should be diagnosed as soon as possible by a reputable and certified auto repair station.
 
Our recommendation is you have a certified smog repair shop conduct a full system diagnosis. Along with the "Check Engine" light being illuminated, there are stored computer codes in the engine control computer which the smog station will be able to retrieve and use for diagnosing purposes. These codes more then often will direct the smog technician in finding the fault.

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Question: My vehicle passed the emissions test but failed the smog check because of the check engine light. I have the OBD Fault Codes: P1443 Manufactures specific code.... With that number can you tell me what need to be replaced or repaired.  Thanks.. I'm a retired Vietnam Vet on Social Security and don't have the funds to just take the vehicle to the dealership for the $100 fee plus repairs.

 

Answer: The problem could be the Canister Purge Assembly. This assembly connects the intake manifold to the charcoal canister and the assembly is made up of hoses, a valve and a sensor. On a 1997 Ford Ranger vehicle, it is located near the front of the engine compartment on the driver’s side (the canister is right behind the driver’s side headlight). Apparently, if there are any cracks in the hoses, or if the valve or the sensor wears out, this will cause the check engine light to come on, and return the P1443 code. After looking around on the web for a couple of days, I was lucky enough to find a few part numbers for the canister purge solenoid/flow sensor assemblies. Diagnostic Trouble Code (DTC) P1443 indicates a failure in the EVAP canister purge valve circuit. The Evaporative Emissions (EVAP) Canister Purge (CP) valve controls the flow of vapors from the fuel vapor storage canister to the intake manifold during various engine operating modes.

 

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Question: My Ford truck failed the LPFET test. I never heard of this test before. How does it work?

 

Answer: EVAP Functional Test (LPFET) is in addition to the emissions test. 1976 to 1995 model year vehicles will be tested, which includes all pre OBDII vehicles subject to Smog Check. The most important impact on consumers is that the emission reductions will improve air quality and reduce their health risks. This test is designed to ensure your vehicle's fuel evaporative system is not leaking gas fumes in to the atmosphere. The EVAP test is conducted by a separate smog tool, called the EVAP Test Machine. This tool pressurizes your vehicle’s EVAP system and looks for pressure drops indicating a leak in the system. This system is designed to prevent the release of gasoline vapors into the atmosphere. Although EVAP systems vary they all contain one similar component. This component is the Charcoal Canister. The canister is responsible for storing gasoline vapors from the vehicle's fuel tank/s and carburetor float bowl (if applicable) until the engine is ready to burn them through the combustion process. The charcoal canister is usually located in one of the far corners of the engine compartment. It is normally a black container filled with charcoal pellets that absorb fuel vapors. Not all charcoal canisters however are located in the engine compartment. Some vehicles manufactures have mounted their canisters closer to the vehicle's gas tanks in order to maximize space efficiency. The number one fault which causes vehicle’s to fail the EVAP test is broken, loose or disconnected EVAP fuel lines. It is necessary to trace the entire EVAP system  in order to find the defective section and/or component.