How do I "clear a code" out of my "OBD2" system, MYSELF ?

Error Code: P0303
Description:
Cylinder 3 - Misfire Detected
Possible Cause:
Wiring harness, igniter and fuel injector connectors.
Ignition system. (Spark plugs gaps)
Fuel injector No. 3.
Fuel pressure.
Running out of fuel.
EVAP canister purge valve.
Evaporative emission system.
Low compression, cylinder No.3. (check valve clearance and throttle plate for excessive wear)
Engine control module (ECM).

try moving your fuel injector , switch with another one and re assemble, clear codes and see if the misfire moves with the injector. If the miss fire moves with the injector then replace the injector with a new one. Or if you havnt tried already fuel injector cleaner may work.
remember after you clear the codes you have to drive it for a couple days before it gets e tested. obd2 systems have to be ready or it will fail etest.

code P0303 is a misfire code for cylinder # 3, Possible spark plug, wire/coil or injector problem. P0141, bank1 sensor2, is the upstream oxygen sensor, this code may have been set by the misfire of Cyl #3, the lean condition is being cause by the misfire. Fix the misfire and clear the codes and P0141 should not return. If the vehicle is equipped with Coil over plug system try swapping the coil with any one of the others, test drive and if the misfire code changes to another P0300 code ( P0301, P0302, P0304 etc...) the coil has failed and will need to be replaced.

Trouble Code: P0303

Cylinder 3 Misfire Detected

Possible Causes:


Air leak in the intake manifold, or in the EGR or PCV system.Base engine mechanical fault that affects only one cylinder.Fuel delivery component fault that affects only one cylinder (i.e., a contaminated, dirty or sticking fuel injector).Ignition system problem (coil or plug) that affects one cylinder.TSB 00-06-04-024 contains a repair procedure for this code.Here's what is listed for this code.303 means it's cylinder 3 that has a problem.To check injector,may be dirty,is to trade it out with another cylinder and see if the problem has left cylinder number 3 and it's at where the injector went.Was the spark that you replaced oily or clean.Could be a mechanical problem,bad piston ring,usually a oily plug in this case.Check for leaks by number 3.

Have you tried clearing the code and go from there? Also maybe try unhooking the negative battery cable for awhile and that will reset it as well then see if it comes back to cylinder one. It's usually best to do all plugs and wires at the same time. Coils get expensive so I can see only replacing them when needed

P0301 - Cylinder 1 Misfire Detected.

Causes:
- Improper spark plug at cylinder #1
- Insufficient compression at cylinder #1
- Incorrect fuel pressure
- The injector circuit is open or shorted at cylinder #1
- Fuel injector #1 may be faulty
- Intake air leak

Solutions:
- Perform Injector Service
- Replaced Spark Plug #1
- Replaced Injector #1
- Replaced Ignition Coil #1

P0303 - Cylinder 3 Misfire Detected.
Follow info from P0301.

P0316 - Misfire Occurred In The First 1,000 Engine Revolutions.

Causes:
- Damaged CKP sensor.
- Ignition System.
- Fuel Injectors
- Running out of fuel
- Fuel Quality
- Base engine
- Damaged Powertrain Control Module

Solutions:
Usually the P0316 is combine with a P03XX codes. The P03XX code indicates in which cylinder the misfire occurred.

The error code p0301 ,This code is related to misfire.The cylinder is misfiring. p0301 this is the indication of cylinder number 1 ,that is misfiring.If the code comes up as p0300 this is the indication of random misfire from all the cylinders.But in your case its indicating p0301 this is indication of cylinder 1 misfire.Check cylinder 1 and replace the faulty cylinder 1 to clear the fault.The spark plugs and the wires connecting to spark plugs also needs to be checked. Keep updated with any more query.Thanks.

Trouble code P0043 means: HO2S Heater Control Circuit Low (Bank 1, Sensor 3)Hex code 43 is for a misfire.

DTC 43 indicates a cylinder misfire, but does not specify which cylinder is misfiring. To pinpoint which cylinder is misfiring, you need a scan tool and get the "P" code, as you can see in the chart below. So it is quite possible you're barking up the wrong tree.


If you go to an Autozone they will scan the codes for you, if the CEL is currently on, and tell you the DTCs they find. That will get you closer to the problem.
I'm fairly confident that if you do a complete tune-up, spark plugs, spark plug wires, distributor cap and rotor, that the misfire codes will be taken care of. Be sure you read this, Dodge Ram 1500 Running Rough before replacing the spark plug wires, or if you have already replaced them.

Hope this help (remember comment and rated this)..

Testing your OBD2

Before You Begin
Since all vehicles are not the same please refer to the manual supplied with the OBD2 code reader for vehicle specific instructions.
Is your vehicle compliant?
All cars and light trucks manufactured since late 1995 should be OBD2 compliant. Two factors will show if your vehicle is definitely OBD2 equipped:

• There will be a note on a sticker or nameplate under the hood: "OBD2 compliant”
• There will be an OBD2 connector as shown below

Pin 2 - J1850 Bus
Pin 4 - Chassis Ground
Pin 5 - Signal Ground
Pin 6 - CAN High (J-2284)
Pin 7 - ISO 9141-2 K Line
Pin 10 - J1850 Bus
Pin 14 - CAN Low (J-2284)
Pin 15 - ISO 9141-2 L Line
Pin 16 - Battery Power
Where is the connector located?
The connector must be located within three feet of the driver and must not require any tools to be revealed. Look under the dash and behind ashtrays.
Important info about OBD2

• Can diagnose/check engine problems in all CAN and OBD2 vehicles (1996 and newer) and many of the most popular OBD1 (1981 to 1995) vehicles
• Features unique patented all-in-one screen display and LED display for quick emissions check
• Automatic refresh updates data every 30 seconds when connected to the vehicle - an easy way to verify repair completion
• Code definition can be displayed in English, French and Spanish
• Can be Flash updated with a standard Windows® PC
• Features memory/battery backup for off-car review and analysis

Connecting
Connecting the OBD2 Code Reader is as simple as locating the DLC connector. The DLC connector is usually found under the driver side (left side) of the dash. The cable attaches only one.
Reading the LCD Display
Click to enlarge
Before you start testing, take a good look at the LCD display. The illustration above explains what the various icons mean and how the DTC (Diagnostic Trouble Code) will be displayed. The unit is self-powered by three-AAA batteries and will let you know when they are running low. When connected/receiving power from the vehicle, the CAR Icon will display.
The OB2 code reader is a very simple tool to use. Once it is connected, turn the power on. Once the ignition is switched to the on position, the code reader is checking the system for any stored DTCs.
The meaning of each DTC can be found in the manual supplied with your code reader.

Example: the code reader displays a DTC PO309, Cylinder 9 misfire was detected.
P0298 Engine Oil Over Temperature P0300 Random/Multiple Cylinder Misfire Detected P0301 Cylinder 1 Misfire Detected P0302 Cylinder 2 Misfire Detected P0303 Cylinder 3 Misfire Detected P0304 Cylinder 4 Misfire Detected P0305 Cylinder 5 Misfire Detected P0306 Cylinder 6 Misfire Detected P0307 Cylinder 7 Misfire Detected P0308 Cylinder 8 Misfire Detected P0309 Cylinder 9 Misfire Detected P0310 Cylinder 10 Misfire Detected P0311 Cylinder 11 Misfire Detected
Once you know what the problem is, you have to determine what's causing it. In this case the intake manifold gasket was faulty. Once the repairs have been made, it is time to clear the DTC and check the system to verify the repair.
Clearing the Diagnostic Trouble Code (DTC)
Clearing the DTC is very simple. Press the ERASE button on the code reader. A message will display on the screen; "SURE" for conformation. If you wish to clear the DTC press and hold down the ERASE button again until a message appears on the screen "DONE". If you did not wish to clear the codes and hit Erase by mistake at the screen message "SURE" simply press the link button to return without erasing any DTCs.
When you clear the DTC(s) from the PCM (Power train Control Module)you also clear ALL of the other gathered information that the PCM has collected, including Freeze Frame, Drive Cycle data, manufacture specific enhanced data end everything stored in memory is erased - just like if you cleared the Cache files on your PC.
The vehicle's PCM will need to re-learn the information that was erased. Don't be alarmed!! This is easily accomplished just by driving the vehicle. All you have to do is get driving.

Good luck and check the OBD 2 connection port.

might be the coil pack is bad, wires, plugs, o2 sensors, dirty injectors, catalic converter ( only if you smell rotten eggs ) . cylinders are misfireing.