Engine light fault. There was a bad spark plug and a failed ignition coil. Replaced both the coil pack or spark plug.

I got a fault that said cylinder #6 bad coil pack or spark plug Which is drivers side rear
I replaced the coil pack and replaced all spark plugs. the plug looked fouled & black.
reset the fault and then it came back again, and the after a few days goes away then back again

My car has 65000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hi there. If the light is coming on then shutting off and returning on, then if the issue is for the same coil, there could be an issue with the wiring on the coil plug. Check the wiring on the coil plug and see if the wires are split, broken, or burned. If there is nothing wrong with the plug, then the main engine harness has an issue / short and may need replaced. If you need further assistance with your ignition system, then seek out a professional, such as one from Your Mechanic, to help you.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

What the P0307 code means. When the P0307 diagnostic trouble code is stored by the Powertrain Control Module (PCM), it is an indication that a misfire has been detected in cylinder 7. More specifically, the PCM detects an increase or decrease in crankshaft revolutions per minute (RPM) that exceeds 2%.
What Does Code P0301 Mean? P0301 definition: Cylinder 1 misfire detected. Diagnosis: A misfire can be caused by anything from faulty spark plugs to low engine compression.
What the P0304 code means. The P0304 code will be seen in cars where the ECU has detected that cylinder 4 is not firing properly. The ECU monitors the operation of all cylinders to ensure they are all firing on time, so when one misfires repeatedly, a Check Engine Light is set.
P0307 Causes

Misfires can be caused by many reasons from a faulty ignition system, fuel system, or internal engine failure. The most common reason for this to happen is faulty or worn-out spark plug coil packs, especially if it`s been a while since you had a tune-up.

A P0300 code in association with a check engine light may indicate problems with your vehicle`s ignition. It should be noted that a steadily-illuminated engine light indicates an active misfire, whereas a severe misfire will cause the check engine light to flash. However, there are many causes of a P0300 code.
The random misfire DTC indicates multiple cylinders are misfiring or the PCM cannot identify which cylinder is misfiring. One or more EGR passages may be blocked or partially blocked.
Is it safe to drive with a P0301 code? You should not drive with a code P0301 set since a misfire can cause additional damage to your car. You should deal with the problem right away, taking the car to a mechanic. If the Check Engine Light is flashing, the car is dealing with severe cylinder misfiring.
The P0301 code means that cylinder 1 has a misfire and isn`t burning fuel properly. Bearing in mind that you need air, fuel and spark for combustion, the cause of a P0301 code could come from a few different sources. In any event, a P0301 code is serious and shouldn`t be put off.
While error code P0304 indicates a misfiring cylinder, the root cause can be many. Your car`s ECM may trigger this trouble code due to a faulty fuel injector, a leaking intake gasket, or low fuel pressure, among other things.
You may report a P0304 code if your car indicates a misfire or an ignition or fuel system issue. As a result, it may result in an internal engine failure. This is a significant problem that requires immediate attention.
An engine misfire can be caused by bad spark plugs or imbalanced air/fuel mixture. Driving with a misfire isn`t safe and can damage your engine.
What Does the P0307 Code Mean? Diagnostic trouble code (DTC) P0307 stands for “Cylinder #7 Misfire Detected.” It indicates that your vehicle`s cylinder #7 is misfiring. This means that incomplete combustion is happening inside the cylinder.
If you experience compression loss in one cylinder of the engine, it can cause misfiring and poor vehicle performance. A decrease in power output is a sign of worn-out internal parts. Sometimes, an engine misfire code may indicate compression loss, but first, check the ignition and fuel for problems.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Engine light fault. There was a bad spark plug and a failed ignition coil. Replaced both the coil pack or spark plug.
ANSWER : Hi there. If the light is coming on then shutting off and returning on, then if the issue is for the same coil, there could be an issue with the wiring on the coil plug. Check the wiring on the coil plug and see if the wires are split, broken, or burned. If there is nothing wrong with the plug, then the main engine harness has an issue / short and may need replaced. If you need further assistance with your ignition system, then seek out a professional, such as one from Your Mechanic, to help you.

Need to replace bad spark plug & coil pack on Ford Expedition but not sure what else I need besides the plug and coil pack?
ANSWER : Hi There,
I would recommend having an expert from YourMechanic come to your location to take a look at the vehicle to first determine what the cause of the misfire is if this has not already been done. Engine misfires can be caused by many different problems and are generally caused by either a spark or fuel issue or in some cases, a combination of both. Spark related problems generally will result from things like ignition coils, crankshaft position sensor, spark plugs, spark plug wires or ignition modules not working properly. When the misfire results from a fuel related issue, this is commonly related to a lean fuel condition (lack of sufficient fuel supply to the motor). Fuel related misfires can be caused by many different things such as low fuel pressure, faulty or dirty fuel injectors, a faulty O2 sensor, a dirty or failing mass air-flow sensor, a faulty or dirty idle air control valve or a vacuum or intake leak. When the fuel supplied to the combustion chamber is insufficient, this results in an ignition (spark) that is igniting a less than balanced load of fuel and air. This results in a misfire or an explosion in the cylinder that is much less powerful than the other cylinders. This creates a loss of power that resonates throughout the motor additionally causing other problems with ignition and fuel timing. Due to the number of different things that may cause an engine misfire, the quickest and easiest way to diagnose this type of problem is to hook the vehicle up to a scanning tool which will download any potential fault codes that may have registered in the vehicle’s computer as a result of the poor running condition. I would recommend having an expert from YourMechanic come to your location to diagnose your misfiring problem.

Engine will not stay started. I have replaced idle control valve map sensor spark plugs spark plug wires no check engine light is
ANSWER : You have a problem with the distributor assembly. I recommend replacing the distributor assembly. This will replace all the possible sensors and coil for the ignition and fix the problem you have.

replaced bad coil pack and new coil not sparking car starts but runs rough engine light on blinks sometimes
ANSWER : Hello and thank you for your questions. If your engine was rebuilt about 10 months ago, the question is to determine if the management system has been installed as well. With the symptoms that you are having, it sounds like the coil packs are old and in need of replace. You replaced numbers 1 and 4 and now number 6 is not firing. I recommend replacing number 6, 2, 3, and 5. This will ensure that you have all 6 coil packs that are new.

Just because the coil packs are okay during a test doesn’t mean that they are functioning correctly. Coil packs on Buick vehicles from 1998 – 2005 last between 150,000 to 200,000 miles. I also recommend having your fuel injection system flushed. Unless you have new injectors, the old injectors could cause a cylinder to fail, even though it is working correctly. These symptoms can cause the engine to have a rough idle and rough running during conditions. If you need assistance troubleshooting the rough running condition, I recommend having a professional, like one from YourMechanic, inspect the car and move forward with repairs.

What repairs fix codes P0172 and P0304? I just had all the spark plugs replaced recently.
ANSWER : The P0304 code indicates a misfire has been detected on cylinder 4. The P0172 code indicates that the fuel mixture is richer than the mixture control can compensate for. It’s possible that they are related, but not necessarily. Rich mixture can be caused by excessive fuel pressure, or sometimes by leakage at a fuel injector. If your misfire is caused by leakage at injector number four, then it’s likely that the two codes have a common cause. It’s also possible that you have had a spark plug foul because of a rich mixture. Again, that would be a common cause. But it is also possible that you have a failure in the number four ignition coil, they are not uncommon. In that case, the P0172 would be a separate issue altogether. If I were working on the car, I would try to determine the cause of the over rich mixture and then work from there. In any case, you need to have a qualified technician check this thing out. Contact Your Mechanic and they can send a technician to your home or office to check out your car and tell you what needs to be done.

Spark plug chaos. Rubber stoppers are preventing the spark plugs from coming out.
ANSWER : Hi there. Try using a pair of small needle nose pliers to pull off the rubber boots from the spark plugs. As you pull, twist the rubber boots to break them free. If you cannot get the rubber boots off, then try using some mineral oil on the boots to aid them off, then clean off the oil with soap and water with degreaser. If you need further assistance with removing the boots from the spark plugs, then seek out a professional, such as one from Your Mechanic, to help you.

Diagnostic code read o2 sensor bad, replaced o2 sensor, cleared code but engine light came back on, is it caused by bad air filter
ANSWER : Hello there. Typically jump starting a vehicle doesn’t trigger an OBD-II error code. However, one of the most common misdiagnosis issues with the P-2270 is replacing the O2 sensor before diagnosing if there are any exhaust leaks. Obviously, you’ll want to check for the exhaust leaks first, repair the damaged component, and then clear the codes before scanning the vehicle again. Sometimes the electrical harness attached to the O2 sensor is damaged or dirty which will also trigger this error code. The noise and vibration may be an indicator of a loose exhaust pipe, which may be the source of the error code staying on. If you need any help, have a technician from YourMechanic come to your home or office to diagnose your Check Engine Light and make the necessary repairs.

Changing spark plug or ignition coils
ANSWER : Changing spark plugs at 46000 isn’t necessarily a bad idea, but mostly I say that because it will keep them from seizing to the cylinder head. Most late model cars like yours can run a set of plugs for longer than that. As for the coils, If the car is not misfiring, I don’t see why you would want to change them and neither does the maxcare company. If the car IS misfiring, then the check engine light will come on and it will set misfire codes. So I don’t see why it would be necessary to do it just yet. If you want to get a third opinion on that, you can contact Your Mechanic to have a technician come out to your home or office to check out your BMW and tell you just what it needs.