I want to what is the issue if the code number is P0306?

While I driving check engine light came and was flushing. I checked that in workshop by computer and it's show (cylinder 6 misfire detected P0306)
And I replace the coil for this cylinder but it came again. what can I do?

My car has 292000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hello there, many faults will cause a misfire in cylinder 6 with your 2007 Lexus LS460. You have done great in replacing the coil pack as these can defiantly cause the misfire. Other potential causes are the spark plugs, fuel injector, vacuum leak, wiring harness fault, or a failing cylinder. If you’d like further help, a qualified technician, such as one from YourMechanic, will be able to diagnose the cause misfire and perform any repairs to get your vehicle running normally again.

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The code P0306 indicates that cylinder 6 is misfiring. A misfire usually happens when the ignition timing is wrong. When your car consumes fuel and generates electricity inside a chamber known as the cylinder, your vehicle moves. Most engines have four, six, or eight cylinders, with more cylinders implying more power.
The P0305 /P0306 code, cylinder 5/6 is misfiring or is randomly misfiring. Maybe check for vacuum leaks as a first step, with engine running(spray starter fluid around the intake manifold base, throttle body, injectors, vacuum lines etc.)
Code P0306 is triggered when the crankshaft sensor does not get an acceleration of the crankshaft from cylinder number 6 firing properly indicating the cylinder is not contributing to the engine power.
Oxygen Sensor – Do you remember when was the last time you got your car Oxygen Sensor checked up? A faulty Oxygen Sensor can cause a lot of issues like displaying P0306 code.
If you receive an OBD-II scanner error code P0306 problem, it means that one of the cylinders is not firing.
P0306 is for a misfire. Replacing your plugs and ignition coil most likely fixed this. P0206 is an injector fault, or faulty wiring to the injector. As you have been working on the engine i would look for a loose wire to the injector, as you have probably misplaced it when changing the plugs.
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.
Repairing or replacing a cylinder can range from $100 to $1,000. Different causes for misfires cause different severities of damage that each cost varying amounts to repair. These damages are: Slower fuel delivery issues can cost anywhere from $200 to $1,000.
P0300 Random, Multiple Misfire Detected means that your car`s computer (PCM) detected that there is a misfire in random or multiple cylinders. Code P0300 is often related to bad spark plugs or spark plug wires but could be caused by a number of issues relating to ignition and the air-to-fuel ratio in the cylinders.
Misfires don`t simply go away – they need to be addressed immediately. Even if they don`t get worse, they certainly won`t get any better unless you take the car to a mechanic.
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.
A faulty crankshaft sensor will cause your engine to misfire as incorrect fuel injection readings weigh in. When this problem becomes especially apparent, the engine may stall and have difficulty restarting.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I want to what is the issue if the code number is P0306?
ANSWER : Hello there, many faults will cause a misfire in cylinder 6 with your 2007 Lexus LS460. You have done great in replacing the coil pack as these can defiantly cause the misfire. Other potential causes are the spark plugs, fuel injector, vacuum leak, wiring harness fault, or a failing cylinder. If you’d like further help, a qualified technician, such as one from YourMechanic, will be able to diagnose the cause misfire and perform any repairs to get your vehicle running normally again.

I have a Code P0601 on the PCM. I replaced the PCM, and now I have a code P0118, code P0123, and code P0193.
ANSWER : Hi there, the short answer to your question is no . A PCM with a P0601 (which is a memory module error in the PCM) cannot reliably retrieve codes for the codes you list (P0118 – coolant temp sensor, P0123 – throttle position sensor, P0193 – fuel rail pressure sensor.

Most likely, the P0601 prevents the PCM from getting any codes from the engine sensors. The memory module error may cause in data corruption for collected sensor values, lose of data over multiple sampling periods, or failure of the data collection to work at all. Replacing the PCM was a necessary expense.

If you need assistance with the "new" codes, I would recommend having a Check Engine Light inspection completed by a mobile, professional mechanic, such as one from YourMechanic, to diagnose the new error codes and get an accurate assessment of the repairs needed.

My car want start and when it do it shut down and want start until 30 minute or so. Now it want do nothing
ANSWER : When a car turns and won’t start, it is called a "crank no start". When this occurs, the first thing you need to do is see what is missing. All internal combustion motors need spark, fuel, injector pulse and camshaft timing to run. If one of these is missing, you have a crank no start. Diagnose the car and see what is missing.

The GM 3.8l motor has been installed in Buicks, Pontiacs and Chevrolets for decades. Particularly during the 90’s and early 00’s, these motors have used an ignition module with three coils mounted to it. This module is prone to just this type of failure. When it gets too hot, it quits working. When it cools off, it starts again. It can also display intermittent no start conditions. This is a pattern failure on this particular motor. Before I would ever replace the module, I would check for spark and injector pulse. If it just lacks spark, I would check for a crank sensor signal and replace the ignition module.

Before we get too far ahead of ourselves, do a few tests first:

Check fuel pressure. If there is none, check the fuse and the relay.
Check for injector pulse with a noid light. If this is missing, I would suspect a crank sensor. It could be a bad Power Control Module (PCM). (PCM’s are very rare to fail. I have never changed a PCM on one of these cars.)
Check for spark with a spark tester. If it is lacking spark but has injector pulse, suspect the ignition module.

If all these are present, I would take a compression test of all the cylinders. If camshaft timing is off, several of the cylinders will have significantly lower compression. Also, camshaft timing won’t start sometimes then not others; it will either start and run bad or it won’t start at all. It may sound like it is trying to start, but it won’t start.

If all of this sounds to daunting, I recommend booking a car is not starting inspection with YourMechanic

Good luck!

It threw a code 21 , throttle position sensor bad code. i replaced it and the code went away but i still have no spark.
ANSWER : Hello and thank you for contacting YourMechanic. The problems that you are encountering with your vehicle, could be caused by the harness to the Throttle Position Sensor (TPS) or the computer itself.

Check the harness to the TPS for any debris or any corrosion. Hook up a paperclip to the harness and turn on the key. Use a multimeter and check for voltage at the pins of the harness. Make sure that the ground on the sensor is grounded and has no resistance. If you find that the harness is having too much resistance, then I recommend having the main engine harness replaced. If you have replaced the harness and still have the same problems, then the computer will need to be flashed or replaced.

I recommend having a professional, like one from YourMechanic, come to your home to diagnose your car’s no start condition before replacing any parts.

Code P0304 (spark plug and COP already replaced – reset code and still have a miss on 4 cylinder.
ANSWER : If the fault is now pinned down to one cylinder, a possibility is a faulty fuel injector. Faults can be of various sorts: injector leaks, the injector driver in the ECM, the injector itself in terms of the electrical solenoid/circuit. But, there are other possibilities and all will have to be tracked down until the fault is found: Faulty oxygen sensor(s); Burned exhaust valve; Faulty catalytic converter(s); Poor compression in that cylinder; Defective computer (rare). To get this resolved, the recommended service is a misfiring diagnostic. If you request that service, the responding certified mechanic will get this diagnosed and resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic.

Can i retrieve CEL code from car … forgot what code it hade in my car .. put headgasket sealer and i erase the code ..
ANSWER : Once a trouble code is erased, it cannot be retrieved. The engine controller does not have a "recycle bin" like they have on Windows. If the car still has a problem, the code will come back up after some driving. However, the controller will not turn on the CEL until it has seen the malfunction on two separate "trips." A "trip" is a driving cycle where the car is started cold, driven until it is fully warm and through a certain number of accelerations, and shut down. So you might not see the CEL for a couple of days. As for the "head gasket sealer," I wouldn’t hold out too much hope of that solving a problem. At the very best it might put off the symptoms for a short while. If you need help interpreting codes that come up, or solving a head gasket issue, contact Your Mechanic. They can send a technician to your home or office to read the codes on your car and help you decide what to do.

Service engine warning, MAF code and O2 sensor code, along with check suspension light are turned on
ANSWER : Hello, it sounds like you have quite a few things going on. I am going to do my best to break them down for you.

First if the engine is very loud when idling and the belt has already been replaced, there may be an issue with the tensioner or idler pulley.
Next, the Navigator is known for needing service to the air suspension system as it gets up in miles, the most common causes of these are the air struts themselves have failed, or one of the air lines has a leak.
Lastly, if the O2 sensor and MAF are continually coming back after the sensors have been replaced, the most common cause would be either an exhaust leak or a vacuum leak.

Qualified technicians such as the ones at YourMechanic will be able to diagnose these issues and recommend the best path to repair, starting with a diagnosis of your warning lights.

EGR code, Cylinder 4 misfire code 0304 detected.
ANSWER : Hi there. The Exhaust Gas Recirculation (EGR) valve may be not designed for the emissions requirements for U.S. standards. If the EGR is pulling from cylinder number 4 and after replacing the EGR and the computer detects a misfire, then the EGR is malfunctioning and not responding. When you close off the tube to the EGR and the EGR light comes on and the misfire light goes out, then the EGR is not responding to your emissions system. I recommend replacing the EGR with the OEM specified part for the engine and all of the issues should go away. If you need further assistance with your misfire and EGR, then seek out a professional, such as one from Your Mechanic, to help you.