Five Things About Your Car ,you Can Do It Yourself
Replacing the Alternator
In most cars, a warning light will tell you when the alternator is dying. If not, you'll know soon enough when your car stalls (from running off a depleted battery) or won't turn over when you try to start it. Novice mechanics can replace dead or dying alternators as long as the alternators are accessible from the top of the engine. (If they're down around the bottom of the block, they can be impossible to see and you have to work by feel to get them out and replace them; that takes experience.)
To do the job, you'll need wrenches, including a socket wrench. Some cars might also require a special tool to take the tension off the belt. And be sure to do things in the proper order. Unbolting the alternator before dimensioning the belt could cause both of them to bind up so that you won't be able to budge either of them.
Replacing the Oxygen Sensor
A common problem that trips the Check Engine light on your dashboard is a faulty oxygen sensor. This is one of the many times you'll need an OBD II scan tool, at least if your car is a 1996 or newer model year. If the scan tool points to an O2 sensor, be aware that vehicles can have as many as four O2 sensors in the exhaust system""one or two before the catalytic convector and one or two after. They look like spark plugs, and your diagnostic tool might be able to tell you which one needs replacing. (If not, you'll need someone with a higher-tech scanner to identify it.)
The O2 sensor can be removed with an open-end wrench, but you should buy a socket specifically designed for the sensors from your parts dealer because it will have a groove for that outgoing wire. Spray some penetrating oil on the base of the sensor before attempting to turn it with a wrench; it'll make the job easier.
Changing Headlight Bulbs
Novice mechanics can change their headlight bulbs but accessing the bulbs can be complicated. Once you've opened the hood, see if the three-wire plug at the back of the headlight assembly is visible. If not, you'll have to jack up that side of the vehicle, remove the wheel, and see what's necessary to loosen the fender panel. (The panel is held in place with fasteners that are unique to each car model.)
Once you can reach the headlight plug, remove it by unfastening the clip, screw cap, or plastic catch that holds it in place, and pull out the bulb. After you pull out the bad bulb, be sure to hold the replacement bulb by its plastic housing. Don't touch the glass, not even with latex gloves.
Replacing the EGR Valve
That Check Engine light might also come on if you have a faulty exhaust-gas-recirculation (EGR) valve. EGR valves are pollution-control devices that reduce nitrogen-oxide emissions by sending a little exhaust gas into the intake manifold. If your EGR valve is faulty, you'll notice rough idling, engine knocking, poor fuel consumption, overheating, or even a failed emissions test. Once you've found the EGR valve (usually at the back of the engine bay on the driver's side), disconnect the electrical and vacuum lines leading into it and unscrew the valve with a socket wrench. That's all you have to do before installing the replacement valve.
Fixing a Leaky Sunroof
If your sunroof is leaking for reasons other than a crack in the glass, the problem is probably plugged drain holes. Open up the sunroof and clean any debris in the tracks. Then find the drains, which are usually in the corners. If you don't have an air compressor and a "wand" for the air-compressor hose, you might try going to your local convenience store and using their compressed air to shoot blasts into the drains to clear them. You could also try unclogging the drains with a section of wire coat hanger. Just be gentle when you push the wire into the drain line.
In most cars, a warning light will tell you when the alternator is dying. If not, you'll know soon enough when your car stalls (from running off a depleted battery) or won't turn over when you try to start it. Novice mechanics can replace dead or dying alternators as long as the alternators are accessible from the top of the engine. (If they're down around the bottom of the block, they can be impossible to see and you have to work by feel to get them out and replace them; that takes experience.)
To do the job, you'll need wrenches, including a socket wrench. Some cars might also require a special tool to take the tension off the belt. And be sure to do things in the proper order. Unbolting the alternator before dimensioning the belt could cause both of them to bind up so that you won't be able to budge either of them.
Replacing the Oxygen Sensor
A common problem that trips the Check Engine light on your dashboard is a faulty oxygen sensor. This is one of the many times you'll need an OBD II scan tool, at least if your car is a 1996 or newer model year. If the scan tool points to an O2 sensor, be aware that vehicles can have as many as four O2 sensors in the exhaust system""one or two before the catalytic convector and one or two after. They look like spark plugs, and your diagnostic tool might be able to tell you which one needs replacing. (If not, you'll need someone with a higher-tech scanner to identify it.)
The O2 sensor can be removed with an open-end wrench, but you should buy a socket specifically designed for the sensors from your parts dealer because it will have a groove for that outgoing wire. Spray some penetrating oil on the base of the sensor before attempting to turn it with a wrench; it'll make the job easier.
Changing Headlight Bulbs
Novice mechanics can change their headlight bulbs but accessing the bulbs can be complicated. Once you've opened the hood, see if the three-wire plug at the back of the headlight assembly is visible. If not, you'll have to jack up that side of the vehicle, remove the wheel, and see what's necessary to loosen the fender panel. (The panel is held in place with fasteners that are unique to each car model.)
Once you can reach the headlight plug, remove it by unfastening the clip, screw cap, or plastic catch that holds it in place, and pull out the bulb. After you pull out the bad bulb, be sure to hold the replacement bulb by its plastic housing. Don't touch the glass, not even with latex gloves.
Replacing the EGR Valve
That Check Engine light might also come on if you have a faulty exhaust-gas-recirculation (EGR) valve. EGR valves are pollution-control devices that reduce nitrogen-oxide emissions by sending a little exhaust gas into the intake manifold. If your EGR valve is faulty, you'll notice rough idling, engine knocking, poor fuel consumption, overheating, or even a failed emissions test. Once you've found the EGR valve (usually at the back of the engine bay on the driver's side), disconnect the electrical and vacuum lines leading into it and unscrew the valve with a socket wrench. That's all you have to do before installing the replacement valve.
Fixing a Leaky Sunroof
If your sunroof is leaking for reasons other than a crack in the glass, the problem is probably plugged drain holes. Open up the sunroof and clean any debris in the tracks. Then find the drains, which are usually in the corners. If you don't have an air compressor and a "wand" for the air-compressor hose, you might try going to your local convenience store and using their compressed air to shoot blasts into the drains to clear them. You could also try unclogging the drains with a section of wire coat hanger. Just be gentle when you push the wire into the drain line.
Source...