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Was driving home yesterday and had my engine light start flashing. It flashed for about 10 seconds and then went away. Ordered a cheap OBD 2 Scanner online and it reads as a P0300 “Random/Multiple Cylinder Misfire.”
These are the readings I got regarding misfires and I need some help understanding them.
What is the test number meaning?
also side note, the “misfires count last” were all zero.
All of these inexpensive code readers at best can read and erase DTC’s and that’s about it…different generic OBD2 code readers show different values and I don’t know if “test” on yours is your misfire count and looks like cylinder 8 has the most at 31…flashing MIL is a catalytic converter damaging misfire so if it returns I’d have the car repaired ASAP…maybe one of your plug wires is not seated properly so you can initially look at that…anything beyond plugs and plug wires are normally beyond the diagnostic capabilities of DIY’ers.
C7's do have a penchant for popping thie plug wires off the spark plugs or coils . Pull the wires and put a tiny amount of dielectric grease in the boot on both ends , this will allow you to feel the wire clip on to the plug and coil....
Has there been anything added or done to your car lately? All of the cylinders doing it, is interesting. What fuel do you use?
Nothing added, I use premium fuel (93 octane) at all times. Have been driving on the fuel for a couple of days now so not sure if it’s that. I do have an oil change Monday though, so I will make sure I ask everything I can
C7's do have a penchant for popping thie plug wires off the spark plugs or coils . Pull the wires and put a tiny amount of dielectric grease in the boot on both ends , this will allow you to feel the wire clip on to the plug and coil....
Dave
Will have to try that, I was looking the spark plugs and wires earlier and everything looked pretty snug.
All of these inexpensive code readers at best can read and erase DTC’s and that’s about it…different generic OBD2 code readers show different values and I don’t know if “test” on yours is your misfire count and looks like cylinder 8 has the most at 31…flashing MIL is a catalytic converter damaging misfire so if it returns I’d have the car repaired ASAP…maybe one of your plug wires is not seated properly so you can initially look at that…anything beyond plugs and plug wires are normally beyond the diagnostic capabilities of DIY’ers.
C7's do have a penchant for popping thie plug wires off the spark plugs or coils . Pull the wires and put a tiny amount of dielectric grease in the boot on both ends , this will allow you to feel the wire clip on to the plug and coil....
Dave
Just DON'T put dielectric grease on the metal contact points! Doing this will really screw things up.
I am trying to figure out what,,,, Cy 1.2, Cy 1.4, Cy 1.5, Cy 1.6, ETC means. Is this 8 different readings from Cylinder 1
Thats just one of the problems with inexpensive (cheap) OBD readers.
They probably got a glitch in their software that makes the screen read weird, but, hey, it was cheap and they are not going to fix the issue.
Try and get a good scanner on the car and you will get a good answer.
Good luck.
PS: Yes I do have an inexpensive OBD reader (Actron, one of the better readers fast and easy) but if anything looks weird or a involves a detailed trouble shooting procedure I pull out my Autel scanner.
Yes I know that money is tight now days and you just want it fixed. Also 98% of people don't want to become a diagnostic tech to fix one issue spending a lot of $$$ for a one time use tool but thats just where cars are today in complexity.
Last edited by Tinkertech; Feb 16, 2025 at 08:47 AM.
My thought, it was doing multiple tests on just cylinder 1. as in Cy1 test 1, Cy1 test 2, Cy1 test 3. I'm not saying I know this, I am just asking the question. For a new device, it's hard to believe they would label it this way. The real test would be if there is a Cy1.9 test.
Yes, it is probably just cheap Chinese junk.
I understand it could be a typo design of the screen. But do you know this for sure?
It's not a typo ... its the low resolution of the screen screen , the lower case L looks like a 1 .... ...
Why do you have to question everything in every post ? ... , if you have ever have seen a misfire count print out from GDS2 or TECH II you would understand that this is standard practice to list the data just likej this . TECH II has the same low resolution , but GDS2 is windows based so it's much more readable
Take my word for it ... that data is by cylinder... go ask the manufacturer if thats not good enough for you
Now stop highjacking the OP's thread with nonsense questions and stick to his problem .....
My thought, it was doing multiple tests on just cylinder 1. as in Cy1 test 1, Cy1 test 2, Cy1 test 3. I'm not saying I know this, I am just asking the question. For a new device, it's hard to believe they would label it this way. The real test would be if there is a Cy1.9 test.
Yes, it is probably just cheap Chinese junk.
No , this is not a a snapshot test , it displays like this as it's live data that will change .... on this model you have to advance thru each cylinder because of the screen size . On better quality testers with higher resolutions you will see all cylinders displayed on one screen which makes it much easier to see which one , or many are the problem .
Most cars , especially high performance cars you will see some random misfires , the misfire counter has a threshold to reach before ECM will light a CEL , exceed that threshold by X percent and the ECM will signal a blinking CEL which as you know means "shut the car down" as there is a major misfire going on
----- 98% of people don't want to become a diagnostic tech to fix one issue spending a lot of $$$ for a one time use tool but thats just where cars are today in complexity.
I am pretty impressed with the free scan I get at AutoZone.
Random Cylinder Misfire
