You Failed Your Emission Smog Test? Here's Your Next Step

by: Richard Trent


Everyone knows for sure that to drive in our North American cities, we have to pass emission smog test. This is required so we can protect our atmosphere and at the same time, save on gas consumption. However, it is almost always a nightmare to pass such test because you either have to bring it to a garage or fix it yourself. Going to a garage is not a problem if you have money but what do you do if you have to fix this yourself? How do you start? What kind of tools do you need? And where do you acquire the information to repair this problem?

Sometimes, it is very intimidating to bring your vehicle to a garage especially when you consider the cost: (1) cost of scanning the codes including the initial one hour troubleshooting which can ran you between $100-$150 (depends on the type of vehicle) (2) additional $100 per hour for the time the mechanic actually starts the repair. In the end, your total cost can easily reach about $300-$800 to repair one code. But this can easily escalate if there are additional codes found.

So does it look attractive to fix it yourself? One example on how a knowledgeable driver can repair his own vehicle by using the check engine light displayed in his dash panel: My 2001 Ford F150 Pick up truck has failed the smog test and this code P0402 (EGR flow high) came on the other day on my vehicle. I tried to fix this myself and when I introduced vacuum to the egr valve port at idle, the engine quit which tells me that the valve is OK. The engine seems to run OK except this nagging light that will surely fail my smog test. Is there a common fix for this code so I can pass emission test?

Analyzing his problem by using my common fixes database, his problem is familiar and this is what I suggested to him: There is a common fix for this and most of the time it needs the replacement of the DPFE sensor. This sensor looks like a small box with 2 ports coming from the exhaust. The sensor is located between the valve cove and throttle body with tubes running from it. This sensor measures the exhaust back pressure when the EGR valve is activated. The passages (tubes) for this sensor can get cracked and leak to trip the code but there has been a lot of failure on the sensor itself. Also, if the tube has a build up of carbon and restrict the flow; the code can be set too. To check, measure the signal voltage of the sensor using a wiring diagram. Max reading is about 0.9 volt and any reading higher means you have to replace the sensor.

Being one of my subscribers, he saved himself the cost of scanning after reading my courseware but had to buy a vacuum pump for $20. He ended replacing the DPFE sensor which he bought from a Ford dealership. He also bought a digital voltmeter for $100 and after paying for the other hand tools, his total expenses are about the same amount had he visited a garage. But these are the major advantages: he now has a set of tools, built up his self-assurance and he is now ready for the next vehicle problem if it occurs.

Does this appeal to you? If it has, then you are ready to hug the new internet miracle by providing you the latest electronic vehicle information. You can read it at my blog at: http://www.check-engine-light-codes.blogspot.com


About The Author

Mr. Richard Trent is an avid publisher of automotive websites and blogs including this blog that helps car owner save money on car repairs. Please visit: http://www.check-engine-light-codes.blogspot.com.