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