P0304 – Cylinder 4 -misfire detected
Last Updated 2017-08-26
ASE Master Tech
|Code||Fault Location||Probable Cause|
|P0304|| Cylinder 4 -misfire detected |
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|Engine mechanical fault, wiring, ignition/fuel system, injector, ECT/MAF sensor, ECM|
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Table of Contents
- What Does Code P0304 Mean?
- What are the common causes of code P0304 ?
- How do you troubleshoot code P0304 ?
- Get Help with P0304
What Does Code P0304 Mean?
A misfire is just what it sounds like; a cylinder that is not firing as it should. The P0304 code is caused by a misfire on the number four 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 P0304 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.
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!
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 P0304 ?
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 P0304 code, the causes could be:
- Cylinder #4 Spark Plug
- Cylinder #4 Coil
- Cylinder #4 Wiring
- Cylinder #4 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 P0304 ?
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.
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I have a 2014 dodge ram 1500 with a 5.7 and getting back a error 305 misfire. Changed out plugs and coil and still sends out code
Well, I’m guessing that the next thing you’d have to check is fuel injection and cylinder compression. I want to confirm, though, that you are getting P0304 or P0305? If you swap coils 3 & 5, for example, does the DTC follow the coil?
Olá pessoal, o teste indica P0303, mas o carro qdo pára, por exemplo no sinal, em D, fica trepidando, tremendo, algumas das vezes após ter rodado por um bom tempo, o motor apaga do nada. Nissan Tiida 2010 Flex, uso apenas gasolina aditivada. Alguém por aí tem uma dica, por favor.
Ciao a tutti.
Auto mercedes anno 2004
clk a209.442 cabriolet
1.8 kompressor 120 kw (163cv)
benzina cambio manuale.
Mi riporta questi codici errore
P0301 p0302 p0303 p0304
Il mio problema è un avvio difficoltoso.
Auto parte sempre ma solo al terzo giro di chiave.
Ho controllato e pulito gli inniettori erano buoni.
This code I find out foult found igition coil short
Hi, I have 2012 Subaru, miss on #4, moved plug, coil, injector to different cylinders, it stay with #4. Compression is 120psi, and unplugging components on #4 and it does change the note of the miss. The cars got 136,000km on it
I have a 2002 Chevy cavalier. 2.4 liter. 4 cylinder. Basically I was driving down road doing about 50 mph and very briefly I heard a sound of like dragging on the ground like a muffler or something but I know that was not it. But the sound was very brief of metal on the right front side dragging on the ground and all of a sudden my car just dies. The sound was very brief of metal on the right front side dragging on the ground and all of a sudden my car stoped running. I coasted to a stop. Then my car won’t start back up. It turns over the battery sound very strong so I couldn’t be the alternator. The battery isn’t dead. so I know I’m confused on what it could be.I put the computer read off and it read off P0304. I looked it up and its says misfire 4 but as I read it said nothing about cavalier on there but that’s what it read.
Hi all. I have had a diagnostics test done on my car because engine management light came in while i was driving. The car also started to shake while i was driving. I pulled over and turned off car. Shortly after i turned car back on and the problem was still there. Breakdown came and done the diagnostics on car. Came back with cylinder 4 problem and that the was also a fuel injection problem an a open circuit. Not sure what this means. The car was then taken to garage were car is under warranty with. They have told me that theu can’t find any fault with car. Would this problem only happen at certain times while car is running. Any info would be much appreciated
I changed spark plugs wires and coil two codes came out before wich was 0304 and 0304 P now still stalling just code 0304P came out still chek ligth I have a Chevrolet Venture 2003 thanks
good day, did you solve the fault? I have a similar problem that you did?
A single cylinder misfire can be caused by a problem with fuel or spark delivery. It can also be an engine mechanical problem. I suggest you follow the steps outlined in this article to determine the root cause: http://www.troublecodes.net/pcodes/p0301/
min car BMW318 E90 modell 2007
P0304 – Cylinder 4 -misfire detected
after chaking all iam see problem i injektr tow wairs one+ and one- flash
when start motor -flash wair- flashing abaut 30 sek. stop flashing and the motor vibrition
I’m sorry, but I’m not sure this got translated properly. I cannot understand your question.