Hello -

On my way home from work today, my CEL flashed a few times slowly, then went away. It did this another time or 2, before permanently turning off. I continued driving home (was about 10 mins away) and stopped by my parents to use my dad's OBD2. It said Cylinder 5 misfire detected, P0305.

I guess my question is, if the CEL stopped blinking and does not come back on, how big of an issue is this potentially? Like if the detected misfire were to continue, would the CEL continue to blink? The fact that it is no longer on (as of when I got home at least), am I good for now?

 

Always post your vehicle info please.
year/model/miles/engine
Thanks.

 

2016 silverado 1500 5.3 about 72k miles

 

Is it flex fuel?
I would monitor the trouble codes with a good scan tool for a while

 

good question and I don't know honestly - what exactly is flex fuel? I only put regular 87 in it. It does have cylinder deactivation (goes from V8 to V4 based on perceived power needed) but I think that's something different

I guess the only real way to monitor would be to see if the light comes back again? And if it does, scan again to see if it's the same thing (or something different) ?

 

Flex Fuel means you can fill it with ethanol. It would have a badge on it.

You can have trouble codes and no dash light. That's why I said monitor it with a diagnostic tool.

 

Where would this badge be? None that I know of. Sorry for any dumb questions, I've been lucky I've pretty much been issue-free for a long time on vehicles, so I've never had to stretch my knowledge much beyond doing oil changes, filter changes, batteries, brakes, etc.

The phenomenon that you mention of not seeing a dash light despite the existence of an issue, is this isolated to engines with this flex fuel?

 

Not sure. Post your VIN if you want. The engine can be looked up easily.
I specifically asked about FF though, because the GM system is known to cause issues.


No, all vehicles. Some problems just aren't serious or frequent enough to trigger a light. I'm not sure what the threshold is for setting a misfire trouble code, but it's more than one misfire.
Live OBD data can reveal clues about what is causing misfiring eg air flow, fuel mixture issues, etc.
A good tool will also tell your WHICH cylinders are misfiring, and how much, which helps.