2001 sonata V6 spark plug

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).

Might be dirty injector or burned valve. Check the connector on the injector. If good, run a compression test on all cylinders. If compression is significantly lower on #3, the head will have to come off. If compression is good, pull up the injector rail with injectors and wiring attached. Watch the injectors spray as someone cranks the engine.

Without testing we would be just guessing . Hook up a spark tester to # 3 cylinder plug wire , is there spark ? Is the fuel injector for that cylinder squirting fuel , they make tools for checking this . Hook up a fuel pressure gauge an fire the injector , does fuel pressure drop. Could be a engine mechanical problem , compression test . Videos on youtube showing how to do these test's .

could also be a bad coil or ignition wire

p0303 is a mutible engine misfire on number 3 cylinder. the best fix,

A code P0303 may mean that one or more of the following has happened:

• Faulty spark plug or wire
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector
• Burned exhaust valve
• Faulty catalytic converter(s)
• Running out of fuel
• Poor compression
• but first of all check the wires and sparkplugs first!

Code P0303 means that there is a misfire detected on cylinder #3. This could becaused by anything from a worn out spark plug to a blown cylinder head gasket, a faulty fuel injector, a bad ignition coil, or a leaking intake manifold gasket. I have also seen this type of code caused by clogged-up EGR ports in the intake manifold on certain engines. "Freeze Frame Data" stored in your Engine computer along with the fault code is designed to help identify what engine conditions (high speed/slow speed, heavy load/light load, etc.) are producing the misfire. This helps a lot in identifying exactly what is causing the cylinder to misfire.

One way to eliminate some of the possible causes is to swap parts with another cylinder to see if the code changes.

If you have "Coil-On-Plug" ignition, you can swap the coil on #3 cylinder with the coil on #4 Cylinder and swap the #3 spark plug with the #2 spark plug. Then clear the codes and drive the car till the Check Engine (or Service Engine Soon) light comes back on.

If it still gives you P0303, then it is not being caused by the plug or the coil. It could be any of the other possible causes listed above.
If it now gives you P304, replace the bad ignition coil that is now on #4 cylinder.
If it now gives you P302, Then replacement of all the spark plugs is recommended.

P0303 mean Cylinder 3 Misfire.

Consider replacing the Cylinder 3 Spark Plug. If that does not settle it,replace the wires too.

Good luck.

1.Plugs
2. Vacuum leak
3. Injector fault
4. High or low fuel pressure.
Thats the list of things to check.
This is a #3 cylinder misfire.
There is also TSB about #3 injector needing added heat protection. This could definitely be the cause. I start at plugs and go from there.
Hope this helps.
Thank you,
Lee

That is a cylinder misfire code have you had the plugs changed, could be a bad plug maybe bad coil, or injector how does it run

Hello I need a help.
I have 1999 lincoln town car 4.6L V8.They have check engine light on. P 0303 cylinder 3 missfire.
I was changed spark plugs,fuel filter. check compression test 150psi. fuel pressuer 50.
swiching cylinder 1 to 3 fuel injector and coil. but they still have engine code