Check Engine Light Error P0306 Cyliner Misfire

MacK · 11-20-2009, 07:43 PM

So heading home today my check engine light came on. I checked the code and it said "P0306". I have been noticing my engine running slightly rough, but nothing major. It says "stumbling" I assume this is what it's been doing, I truthfully don't know how to describe it..

The error reports:
What does that mean?

A P0306 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #6.
Symptoms
Symptoms may include:

* the engine may be harder to start
* the engine may stumble / stumble, and/or hesitate
* other symptoms may also be present

Causes

A code P0306 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
* Defective computer
According to OBD-II Trouble Code: P0306 Cylinder 6 Six Misfire Detected

I'm flat broke, And I'm at 56,800 miles out of warranty slightly.

How do I reset the computer? Because it gave me the code the FIRST time around, but now it won't give me the code it just says ------ but the check engine light is still on.

I think I'll take it to autozone and have it scanned tomorrow..

**ronjenx** · 11-20-2009, 07:53 PM

Are you the first owner with a delivery date on or after July 26, 2007?

MacK · 11-20-2009, 07:57 PM

Quote:

Originally Posted by ronjenx

Are you the first owner with a delivery date on or after July 26, 2007?

I am second owner. I bought it with 3,000 miles roughly.. Think there's a TSB? Where can I find production date?

**ronjenx** · 11-20-2009, 08:04 PM

You have posted a lot of information already. Is it generic OBDII info?

This is from the 2008 FSM for P0306:

P0306-CYLINDER 6 MISFIRE

Set Condition:
The threshold to set the fault is application specific; it is tied to the level of misfire that will cause emissions to increase to 1.5 times the standard or in some cases 1%. It is always a two trip fault above the calibrated RPM. It takes 1 soft fail to set a malfunction and two trips to set the MIL. Three good trips to turn off the MIL.

Possible Causes

ASD RELAY OUTPUT CIRCUIT

INJECTOR 6 CONTROL CIRCUIT

COIL CONTROL 3 CIRCUIT

IGNITION WIRE

SPARK PLUG

IGNITION COIL

FUEL PUMP INLET STRAINER PLUGGED

RESTRICTED FUEL SUPPLY LINE

FUEL PUMP MODULE

FUEL PRESSURE LEAK DOWN

FUEL INJECTOR

ENGINE MECHANICAL

POWERTRAIN CONTROL MODULE (PCM)

MacK · 11-20-2009, 08:20 PM

I assume it is generic ODBII info... Would this be caused by me or just something that went whacko by itself?

**ronjenx** · 11-20-2009, 08:52 PM

Quote:

Originally Posted by ThomasMack

I assume it is generic ODBII info... Would this be caused by me or just something that went whacko by itself?

If you had just done some maintenance, you could have knocked something loose.
Is it still running roughly?
Pick out the items from the list that you can check.
Some people have had problems with spark plugs. Put a new one in cylinder #6. Or, just swap it with one from another cylinder. See what happens.
Get it scanned to see if there are any other codes set.
If it's not running roughly, have them erase the codes and turn out the light. See if it all comes back.

MacK · 11-20-2009, 09:01 PM

Who has to erase the codes? Can Advance Autoparts do this? I know they can scan the computer. I haven't done any kind of maintenance. However I did recently spray the engine down with water but I always do this because it tends to get muddy ;x

I'm not mechanical at all.. I can change oil and air filter that's about it. It seems like it runs smooth, then kinda "misses" every few minutes.. but only while idling not while moving. Sounds fine running. There's sometimes slight vibrations. Sometimes when I shut off the engine the whole vehicle vibrates - but it's always done this since I had it..

MacK · 11-20-2009, 09:53 PM

OK, so it won't report the error anymore. It just says ----- but the check engine light is STILL on - what does this mean? The error is null it just needs to be reset? How do I reset?

**ronjenx** · 11-20-2009, 10:11 PM

It could be some codes will not show with the readout on the instrument cluster. If there are other codes, that would be why the light is still on.
If the problem no longer exists, the light should go out after 3 good trips.
Anyone with a scanner should be able to clear the codes and extinguish the light.
Try disconnecting the negative battery terminal for a few minutes. That may extinguish the light.

MacK · 11-21-2009, 01:18 AM

Quote:

Originally Posted by ronjenx

It could be some codes will not show with the readout on the instrument cluster. If there are other codes, that would be why the light is still on.
If the problem no longer exists, the light should go out after 3 good trips.
Anyone with a scanner should be able to clear the codes and extinguish the light.
Try disconnecting the negative battery terminal for a few minutes. That may extinguish the light.

Thanks. I'll do this and report back tomorrow.

MacK · 11-21-2009, 03:36 PM

Engine lights went off today... didn't do anything to it. Just shut off. It wasn't giving the error code anymore so I have reason to think it was just a error in the computer or it just happened to "misfire" once.. seems good now :O

**ronjenx** · 11-21-2009, 04:48 PM

Quote:

Originally Posted by ThomasMack

Engine lights went off today... didn't do anything to it. Just shut off. It wasn't giving the error code anymore so I have reason to think it was just a error in the computer or it just happened to "misfire" once.. seems good now :O

Has the roughness gone away, too?

MacK · 11-21-2009, 06:57 PM

It seems too.. wonder what it was..?