2009 G37s Manual Trans, just got my p0300 error code, I recently had this before and after I got my sparkplugs changed, ONE of the ignition coils (out of the six) were replaced but the error is still there. Only p0300 error. Any help? Do people charge to check that (only to check what's wrong)?

 

I don't know anyone that works for free

Telcoman

 

^lol telecomman. but yea most shop including dealer i think charges about $80 diag fee. and if u decide to have them fix it they will credit the fee

 

p0300 is random misfire. your gonna have to take it to a shop that would have the right tools and knowledge to diagnose your problem. and yes people do charge to look into performance problems with cars. i'm just wondering if you like to be paid for the work you do at your job.

 

PM me I'll help you out.

 

I am dealing with misfire issue as well. I would get SES code which would go out on its own. Took in for PA state inspection which led to this diagnosis, since I was told the car would not pass inspection, from service manager which baffles me since I took the car in without any SES code and running good for a 2008 G37S with 156k miles. This is what I was told after the service shop working with engineers took 13 weeks to determine with the conclusion I need a new engine!
"Vehicle entered shop with misfire. Tech found spark plugs cracked and missing diodes on four cylinders. Tech replaced plugs and issues persisted. Found coils inoperative. Replaced coils. Issues persisted. Completed full engine compression test and found normal compression in normal range. Techline contacted for further assistance. DTS was dispatched and evaluated car. DTS found one catalytic converter clogged and recommended replacement of 02 and AF sensor. Issues persisted. Found crankshaft position sensor value out of range. DTS advised replacement of sensor. Tech replaced sensor. Issue persisted. DTS supplied known good ECM and found no change with new ECM. Finalized diagnosis confirms issue internal to motor. All repairs that were made fixed symptoms of the root cause being the engine." and "Per our conversation the connecting rod is the part in question. The DTS (tech engineer) confirmed the issue is inside of the engine. It is not from external controls. All external control components that have been replaced were bad, but it turned out they were symptoms of the problem…. not the root cause. Similar to a medical diagnostic issue, when problems are not straight forward it takes time and treatment to properly/completely diagnose the issue."
Spark plugs and injector flush were performed by Infiniti service shop. By the description you would think the car would not even run. Still trying to get answers on what would cause connecting rod to bend. Midway through this event, they commented my engine was in very good condition with Pennzoil Ultra oil changes every 3k-5k miles and now they say I need an engine which they are offering to cover all parts replaced and install used engine with 6 month warranty for $6500. They recommend I do not drive he car as it is.
Part of the 13 weeks is due to them saying they had not seen this before and car was not misfiring but all sensors indicated so, but no code for cats or anything else.

 

Whoa! that is crazy! Talk about throwing parts at it. did YOU pay for all that work?! Obviously, you need to get a second opinion. After they couldn't fix it the second or third time, you should have taken it somewhere else.

Someone else said their issue with the P0300 was bad O2s.

But jeeze, any decent tech can watch the live data on each cylinder and find out witch cylinder is misfiring. You Have GOT to take that somewhere else.

 

I haven't paid anything yet, the car is still there. I'm waiting for answers to my questions that the Service Manager passed on to DTS. I also contacted the Service Manager at a different service location for their opinion as they are the shop being accused of damaging the spark plug during installation and potentially performing a problematic injector flush. That Manager does not by the story either I've been told. For now I continue to drive their QX60 loaner until get direct answer from the DTS that make sense. Not sure how they can say their is a bent connecting rod while compression still within normal range. Still waiting to hear how exactly they determined that. Also waiting on Consumer Affairs to call back.

 

Man, all this for a single P0300 code? I had the code two weeks ago along with the P0524 (low oil pressure) code. Took it to the Nissan dealership and they spent 3 hours trying to find a problem. Checked oil pressure, valve train, engine timing drove it around and couldn't find a thing. The service tech said that since I didn't drive the car much, sometimes it sits for a Month, he expects that some sensor was causing the problem. His recommendation was to drive it daily and see if there are any repeat codes. I've now put almost 500 miles on the car in two weeks and no SES light. It did come on again the day after I had it in for service, but as I was driving it back to the dealership, the SES light went out. How did they determine that you have a bent connecting rod?

 

After waiting 2/1/2 weeks for DTS report I am told by service manager "I think there may have been a slight miscommunication. I said that I will call you with an update or email you when the DTS reports back to me. The Dealer Technical Specialist will not hand me a physical report regarding your vehilce. The only time there is a written report is when legal issues occur with in warranty vehicles. Unfortunately the answer to our question is not as specific as I would have liked. Without completing a full engine teardown to inspect the specifics/root cause, there is no way to state what component is the prime failure nor can its exact condition be determined." and "Essentially It has been determined that there is damage internally to either a connecting rod or a valve. It is not possible to determin which exactly without performing a full teardown unfortunately. At this point tearing down the engine is only going to drive up costs and will not speed up the process of getting your vehilce situated. I hope this helps your decision." Still not clear if the car is still throwing misfire codes, hard to get answers.

 

Good luck pal. On mine I just cleaned the MAFS an the code went away. Initially idled high by 400 rpms, but now back down to spec. Crossing my fingers.

 

Can anyone answer if the "codes" that Infiniti can read from the car history are all visible to a local mechanic for state inspection? My SES light would come on once in a while but then go out. If the SES light is out and no active or pending code seen by an OBDII tool will the car pass inspection, assuming safety and emission are good? I meet with the dealer tomorrow about my car after 17 weeks, and they say there are still codes (unknown of SES light on), but it is not clear to me if this will cause the car to fail inspection and it is really a problem.

I need to determine if I really need an engine or they are taking the safe way out if they don't know what the issue is since they "assume" it is a bent valve for connecting rod. For example early on they reported "Pertaining to the misfire on cylinder 1, and why it took so long to get the results back is there was actually no misfire on cylinder one, the clogged converter reproduced symptoms of a misfire so closely that even the vehicles computer showed a code for the cylinder 1 misfire, also giving the technicians while driving and testing the same feel as if the vehicle was misfiring as a clogged converter causes poor performance. "

 

To pass inspection you can not have an DTCs, and in my state at least, you can have one group in the 'not-ready' state. So if you have codes, you will not pass. BUT if infiniti is running some kind of manufacturer specific software like a lot of manufacturers run and THAT has codes but not regular OBDII codes, you might be ok. Just ask the tech, he will know the difference, and will be able to tell you if it will pass or not.

 

I picked up the car and paid only for the ones I agreed to (after negotiation). Only details they would tell me is that the car is throwing a misfire code. They said the engine idles rough and "falls on its face at times when hot." They said the car came in with code (not true) and running horrible when I brought it in (not true). I would agree sometimes there is a slight rough idle but not enough to want me to buy a new engine. After I drove the car home I checked with my tool and no codes showing or pending. I drove for 50 miles then took to my mechanic for inspection, which it passed without issues. The car drives the same as when I dropped it off 17 weeks earlier and the following parts were replaced (according to them):
Spark plugs
Fuel injector
Camshaft Position sensor
Catalytic converter
Air to fuel ratio sensor

Since I'm only an electric engineer the service manager noted that I not a mechanical engineer and started to explain different expansion rates with dis similar metals. When I asked are you trying to imply when the engine heats up the valves won't seat properly if they are bent, he changed the subject.

I still could not get and answer as to exactly what sensors and reading actually cause the misfire code to be thrown; anti-knock, O2, air/fuel, etc.

Even though I was told a one point DTS was supposed to contact me directly, eventually I was told by the service manager after repeatedly requesting a DTS report on findings that "The Dealer Technical Specialist will not hand me a physical report regarding your vehilce. The only time there is a written report is when legal issues occur with in warranty vehicles."

Heading back to service today to get the parts that I thought were in my trunk but weren't (forgot to check). Still puzzled how the car would run with their claims of 1 cracked plus and 3 missing diodes.

Service Manager suggested if I get the car to pass inspection I should sell it as the problem will only get worse. So while waiting for them to get car back together, I checked on trade in value on a used 2017 Q60 Sport Red and they offered me $1500 even though I just had them mount 4 new Michelin Pilot Support Sport tires I purchased separately and all the parts just replaced!

This will be my last Infiniti, which is a bummer as I really like the car.