P0300 code

[Pitterpat]

2012 Yukon Denali - 97 - 98K when problem started 2/2019 - Bought car 4/2017 79K miles, now just turned 100K - I have regular oil changes done, about every 3K or so, synthetic.

SES came on took to my Auto place, they put the scanner on it and the code was the one for the oil filter thing behind the engine. I ended up replacing that and they cleared the code. I had to take the top end off (couldn't reach behind, I tried). They cleared the code and off we go.

Next SES light comes on or maybe it basically stayed on. Autozone checked the code and it was P0300. What my Auto place said they have had success with doing is running the engine clean stuff through it from Valvoline. Yes, I trust them, I've been going to the same place for 30 years....my mechanic there has been there for 20 years...he helps me out / saves me $$$ on a lot of things. They are very reputable here in Indianapolis. So to pay $79.00 to have the cleaning fluid run through my car...no problem. That didn't take care of it.

So about 6 weeks ago (some time in March) the SES light went out for about 1 day, it was a rainy day. Why, not sure, then it came back on. Talked to my mechanic and he said I could try changing the spark plugs. I didn't change the plugs when I got the Yukon but did have the oil changed immediately.

Also, my exhaust has the rotten egg smell....especially when I floor it to pass somebody. Besides changing the plugs and wires anything else I should look for?

Thanks in advance.

 

[Kraig]

Rotten egg smell is typically associated with the catalytic converter. If they’re clogged, that could cause misfires.
I’d say you’re about due to change your spark plugs and they might give some clues as to what’s going on in your engine.

 

[Pitterpat]

Rotten egg smell is typically associated with the catalytic converter. If they’re clogged, that could cause misfires.
I’d say you’re about due to change your spark plugs and they might give some clues as to what’s going on in your engine.

Yeah, I was afraid with the rotten egg smell it could be the cat. I'm going to change the plugs and plug wires week after next. Out of town all next week so I don't want to put the expense in when it will sit for a week.
Thanks!

 

[RAFJR]

Yeah, I was afraid with the rotten egg smell it could be the cat. I'm going to change the plugs and plug wires week after next. Out of town all next week so I don't want to put the expense in when it will sit for a week.
Thanks!

what was the solution. Don't post here and then never report back. It's selfish.