# Code P0300 and U0100



## jstahliv (Apr 13, 2016)

I am getting since last october (a year ago) P0300 and just in the last few months U0100. I have put in a new battery, new neg. batt. cable, new coil pack, new intake manifold (cause of STUPID CHECK VALVE FAILURE/MISSING), new spark plugs (irridium/oem type not coppers gapped at .28 IIRC) New valve cover (PCM valve went out)and fuel injector cleaner and different gas. Car worked well a few months after valve cover and intake manifold replacement but now I still have p0300! and the crazy U0100. Any updates and help for me?

52300 Miles 2012 Cruze 1.4 liter turbo 1LT, Only mod is K&N air intake. also have 1000 watt rms amp but was not driving sub at the time of it coming on. Servive stabilitrak and traction control obviosly came on when it was sputtering missfiring. Misfires were very LIGHt and not rough at all. 

I did a normal light drive when it happened first recently (after new parts added) and 2nd time was with a very light launch ( turn of Trac. Control , give gas and let off brake )


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## Blasirl (Mar 31, 2015)

jstahliv said:


> I am getting since last october (a year ago) P0300 and just in the last few months U0100. I have put in a new battery, new neg. batt. cable, new coil pack, new intake manifold (cause of STUPID CHECK VALVE FAILURE/MISSING), new spark plugs (irridium/oem type not coppers gapped at .28 IIRC) New valve cover (PCM valve went out)and fuel injector cleaner and different gas. Car worked well a few months after valve cover and intake manifold replacement but now I still have p0300! and the crazy U0100. Any updates and help for me?
> 
> 52300 Miles 2012 Cruze 1.4 liter turbo 1LT, Only mod is K&N air intake. also have 1000 watt rms amp but was not driving sub at the time of it coming on. Servive stabilitrak and traction control obviosly came on when it was sputtering missfiring. Misfires were very LIGHt and not rough at all.
> 
> I did a normal light drive when it happened first recently (after new parts added) and 2nd time was with a very light launch ( turn of Trac. Control , give gas and let off brake )


Plug your VIN in here to see if there are any recalls for your car: Recalls by VIN

The generic OBD trouble code U0100 is a serious situation where the signals between the electronic control module (ECM) or the powertrain control module (PCM) and a particular module have been lost. There could also be a problem with the CAN bus wiring disrupting communications.


A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.

Read more at: https://www.obd-codes.com/p0300 



As for the electrical, did you really inspect the positive cable as well? I would double check your gaps and reinspect your boots to make sure there are no rips or deformed areas.


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## jstahliv (Apr 13, 2016)

How do I inspect the positive cable? I have had my VIN checked at least 2 times by the chevy dealer, they say all recalls have been performed. When I asked them about negative battery cable special coverage they basically said No and that my vin wasnt listed under that special coverage. What worries me the most is the U0100. How can I check the CAN bus wiring? Just checked vin on NHTSA site, "0 recalls for this vin" [h=1]
[/h]Ty for your quick response.


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## lonewolf04 (May 6, 2016)

Thank link is for recalls only, not special coverage, which is what the neg battery cable is.


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## jstahliv (Apr 13, 2016)

lonewolf04 said:


> Thank link is for recalls only, not special coverage, which is what the neg battery cable is.


Chevy has looked up my vin many times and there is nothing needed. I tripled checked and I have replaced neg bat cable so it doesnt matter and will move one to pos cable and CAN bus maybe. But not sure what to do. How can I check the CAN bus wiring? I checked pos cable and it is secure and doenst seam loose or bad.


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## ChevyGuy (Dec 13, 2014)

Before jumping to the CANBUS wiring, is there anything plugged into the OBDII port?


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## jstahliv (Apr 13, 2016)

I just inspected the OBDII port. Nothing looks to be wrong with the pins and there is nothing attached to it. Last time it was used, was last week when my local mechanic hooked up OBDII scanner to it. FOR FREE. lol That is how I got my codes.


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## jstahliv (Apr 13, 2016)

Are these carse picky with gas? I was getting it at a harvey's for months and got my first tank of sunoco ( i use 93 octane only ever at any statation) in a while. If so , what in the car causes one gas to run better than another? bad plugs/fuel-air mixture / bad emc programming. I just want a car I drive 3 months WITHOUT CODES or this misfire scenario.


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## ChevyGuy (Dec 13, 2014)

jstahliv said:


> Are these carse picky with gas?


A little. If it's hot, it will like premium, or at least mid-grade. But that's just performance - it won't set codes if run on regular.


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## jstahliv (Apr 13, 2016)

I just cant figure out what could cause misfire if I have replace coil, sparks, valve cover, intake man. Could it be 02 sensor running lean/rich and not throwing code?


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## jstahliv (Apr 13, 2016)

Could fuel filter/fuel injector or oxygen sensor be causing problem if no codes are showing up?


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## jstahliv (Apr 13, 2016)

UPDATE!!!!!!!!!!!!! So I kept driving the car and getting misfires and sputtering under load (cold weather mostly but not always) (every misfire results in service stabilitrak/traction control) but eventually i got a solid Check Engine Light (CEL). I got it checked and it was Intake temperature sensor, barometric pressure sensor and humidity sensor codes saying both high and low voltage. After checking everything, I realized they are an ALL IN ONE sensor. It is actually the mass air flow sensor. (most times its just an air intake temperature sensor on the intake , but not the cruze) Paid 90 bucks on CarId for it and ran it this morning after install. Turbo seems to scream over 2500 rpms something i have never heard or at least realized before. Not normally audible after 2500. So unless unless i have any more problems. i would say , all the codes I got where from 3 things for past year. 
1 Intake manifold check valve missing
2 PCV valve cover (valve broke apparently from intake check valve missing)
3 MASS AIR FLOW SENSOR (caused p0300 after fixing first 2, COULD NOT FIGURE IT OUT, as I had new intake manifold, ignition coil, spark plugs, valve cover, neg batt cable, fuel injector cleaner.)

If you fixed your intake man. and replaced valve cover, and still have p0300, and you are throwing parts at it, Mass air flow sensor(MAF) is the thing to check next ( as I did, everything else was new! didnt really need ignition coil I dont think, maybe) 

Codes for MAF sensor where P0097 P0113 P0300 P11C2 P2227 P2228 

PLEASE make sure your intake manifold check valve (search cruze talk for post with pictures) is not missing , and your PCV valve is working before doing ANYTHING.


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