P0302 – Cylinder 2 -misfire detected

What Does Code P0302 Mean?

A misfire is just what it sounds like; a cylinder that is not firing as it should.  The P0302 code is caused by a misfire on the number two 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 P0302 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!

Ignition Systems

Waste spark distributorless ignition systems (DIS) are common on many cars.  Identifying and understanding a waste spark DIS can help with troubleshooting a misfire.

Your car has a waste spark DIS if there are fewer coils than cylinders. The system shares a coil with two spark plugs corresponding to companion cylinders – the cylinders which are opposite in the firing sequence.

The following Youtube video series describes the GM waste spark distributorless ignition system:

More information on the other systems involved in a misfire can be found in the background section of codes P0300 and P0301.

What are the common causes of code P0302 ?

When you encounter a single cylinder misfire, the causes of systemic misfires such as: fuel pumps, 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 P0302 code, the causes could be:

• Cylinder #2 Spark Plug
• Cylinder #2 Coil
• Cylinder #2 Wiring
• Cylinder #2 Fuel Injector

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

What are the symptoms of code P0302 ?

A single cylinder misfire can be accompanied by stumbling or lack of power.  The car can also run fine.

How do you troubleshoot code P0302 ?

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.

BAT Team Discussions for P0302

• Misfire... Need help badly.
  Hi guys. I have a 2002 Mitsubishi Galant ES 4cyl AUTO. ~127k I have done all the maintenance and more. Beginning at like 75K, the car started shaking at idle when in drive. at like 120K, timing belt broke and was brought into a NOOB shop. No bent valve. No damage. Though now, the car's engine sounds...
• 97 Nissan Quest Checking Engine light on - 2nd Cylinder missing fire
  97 Nissan Quest, 95K miles. Suddenly the check engine light went on. Went to Autozone and the scan showed "2nd cylinder missing fire". The error code is P0302. Then found the wire to the 2nd cylinder was "leaking fires" - the rubber insulation was broken and some fires went the metal holder of the w...
• Code P0302
  I have a 1996 Ford Windstar 3.8.Ck engine light on. Scanner shows P0302, misfire on #2. I replaced the spark plug & wire on #2 but after driving light comes on again. What should I look for? Thanks...
• 03 MITSU GALANT
  [quote="Jim Fairbanks"] If you can get the code # and post it back here it would help a lot. . . . Jim [/quote] code is P0302 MISFIRE #2 CYL i did a rough inspection there is power going to injector, i swapped plugs with #2 #2 has a coil pack on top of that one....
• 99 Cougar problem...HELP!
  Depends on what is wrong with the cats exactly. If the cats are restricted, then yes it WILL cause a misfire and blinking check engine. However, you should also have some misfire fault codes in here. You are sure you saw the check engine light "flash" or "blink"? If so, there was a misfire detected....