P0305 – Cylinder 5 -misfire detected

By Mia (Contact Me)
Last Updated 2017-08-26
ASE Master Tech

Trouble CodeFault LocationProbable Cause
P0305 Cylinder 5 -misfire detected Engine mechanical fault, wiring, ignition/fuel system, injector, ECT/MAF sensor, ECM

We recommend Torque Pro

What Does Code P0305 Mean?

A misfire is just what it sounds like; a cylinder that is not firing as it should.  The P0305 code is caused by a misfire on the number five cylinder. The Misfire monitor diagnostic is based on variation in crankshaft velocity. The PCM determines this information using the crankshaft position sensor and camshaft position sensor. A misfiring cylinder slows down momentarily, so by monitoring the cam and crank sensor signals, the PCM can calculate when a misfire occurs.  A P0305 code tells you only that a misfire has been detected, not WHY the cylinder is misfiring.  That’s why with this code, a thorough diagnosis is mandatory.

Misfire Monitor

Different manufacturers implement OBD-II requirements slightly differently.  The misfire monitor is an OBD-II procedure which identifies a misfire.

The misfire monitor is a “continuous” monitor; it is always checking the crankshaft position sensor for a misfire.  It is important to note that the misfire monitor is very reliant on the crankshaft position sensor signal.  A faulty crankshaft position sensor will misdiagnose misfires!

What are the common causes of code P0305 ?

When you encounter a single cylinder misfire, the causes of systemic misfires such as: fuel pumps, timing problems, EGR valve leaks, or crankshaft position sensors are less likely.  Individual spark plugs, fuel injectors and valves should be carefully examined for the cylinder.  For companion cylinders, the cylinder noted by the PCM may test fine.  Be sure to check its companion in the firing sequence.  For a P0305 code, the causes could be:

  • Cylinder #5 Spark Plug
  • Cylinder #5 Coil
  • Cylinder #5 Wiring
  • Cylinder #5 Fuel Injector

TIP: Check for a technical service bulletin. There could be a known repair for a single cylinder code.  Sometimes the PCM errors.


How do you troubleshoot code P0305 ?

Often, the best way to troubleshoot a single cylinder misfire is to swap ignition components between the misfiring cylinder and a good cylinder.  If the misfire moves with the sparkplug (for example) then the sparkplug would be the cause of the misfire.  If switching components to a good cylinder doesn’t eliminate the original misfire then there could be a problem with compression.  See articles P0300 & P0301 for in depth troubleshooting of the four misfire causes: fuel, spark, timing, and compression.

The following Youtube video describes troubleshooting a GM Vortec engine with a P0305 code:

BAT Team Discussions for P0305

  • 2001 dodge dakota please help....
    Ladies, Gents... I am a Navy guy and trying to fix my 2001 Dakota quadcab 4x4 5.9L. The trans went out so I got it replaced. Then it was great for awhile and the started getting harder to start as the days went by. Checked codes and got p0123 and p0351 and p0152. I smelled sulpher smell so I gutted...
  • Intermittent rough engine.....
    Thanks to all so far for the help..... P0305, cylinder 5 misfire is current code. This appeared shortly after the tune-up with quality parts and re-check of connectors. Check engine light is ON but not blinking. Engine is running rough at idle, but seems better at higher speeds (car has good ac...
  • Cadillac CTS P0300 code
    Any help on this would be helpful. I own a 2005 Cadillac CTS 3. 6L with 71000 miles. It recently began misfiring while I was driving usually on the highway at speed and never at idle. On my way home from work about 2 weeks ago it began getting worse and about a block from home it began knocking r...
  • Please help me find the TSB for my issue
    I have a 2006 Lexus GS300 (V6-3. 0L engine (3GR-FSE)). I took my car to the dealership because the check engine and check vehicle stability control indicators were on. I was told at that time that there is a TSB to replace valve springs in my car. There were two missfire codes that were found ...
  • Jeep Grand Cherokee '02 - recurring (approx once a month) misfires
    Well it happened again - and after the Seafoam treatment. It was exactly one week after the last time. Here is the data: June 22, 2009 ************* P0305 P0305 FF Data: Fuel System 1: Closed loop Fuel System 2: Closed loop Calculated LOAD: 70.1% Engine Coolant Temp: 206°F STFT Bank 1: -2.3% L...