Help me diagnose a P0300 code...

[Zaks]

I've been having trouble with this for a couple of months. It first started when a chunk of snow knocked out my outside temp sensor. Soon after that, the SES light came on and along with the sensor code (forgot the exact # now), this P0300 came on as well as one or two of the cylinders. Since then, I've replaced all spark plugs (NGK), all coils (bosch -219) and all of the hoses/boots with the CCV valve. Also cleaned out the icv, throttle body, maf, etc. Fuel filter is new as well as is the cooling system (just throwing that in there). I ran both seafoam and another fuel system cleaner my mechanic recommended, with 3 full fuel tanks in total.

My mechanic and I are both stumped, mainly because the car runs perfectly well. No sputtering or any issues with cold starts, holds idle perfectly well whether it's cold or warm and runs really well.

Next on my list is the fuel pump and fuel tank cap.

Just wanted to post on here in case anyone ran across a very odd issue that could throw a P0300 (along with P0301-6). P0300 is for multiple random cyl misfire, and p030x is for a specific cylinder.

Thanks in advance.

[BADCLOWN]

What is the code specifically for? I don't know if I'm overlooking what that code actually means in your post or not.

[Vas]

PO300 is for a multiple cylinder missfire.

If possible, I would smoke the entire intake system and see if you have any vacuum leaks.

[Zaks]

^^ yea forgive me, that's correct. P0300 is for multiple random cyl misfire, and p030x is for a specific cylinder.

Vas I'm going to do the fuel pump as it's due for one anyway and soon after smoke test it if not fixed. Thanks.


Ivan

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[BADCLOWN]

You said your car is running right which is good. GF got a multiple cylinder misfire on her 2012 Beetle Turbo and hit had skipped time due to a failed part

[Zaks]

You said your car is running right which is good. GF got a multiple cylinder misfire on her 2012 Beetle Turbo and hit had skipped time due to a failed part

Yes it's running great, which is the part that's confusing us. But I guess it's a good problem to have :).

Today the SES light turned off after I filled up gas after it went down to almost empty. I noticed the fuel cap seal is a bit worn and the metal surface where you pour in the fuel was a bit dirty, so I did clean that up. I'm hoping with the new cap it stays off, so I'll be testing that for 200-300 miles before doing the fuel pump as well.

[russiamutha]

DISA valve failing/failed
Fuel filter clogged
Fuel filter vacuum line disconnected/broken

I'm betting your DISA valve is failing

Fuel pump on these cars is either working or it does not, feel free to measure fuel pressure on bleeder valve but I doubt it's your fuel pump.

[Zaks]

So far over 800 miles with no SES after only replacing the fuel cap.


DISA valve failing/failed
Fuel filter clogged
Fuel filter vacuum line disconnected/broken

I'm betting your DISA valve is failing

Fuel pump on these cars is either working or it does not, feel free to measure fuel pressure on bleeder valve but I doubt it's your fuel pump.

[BMWCurves]

So far over 800 miles with no SES after only replacing the fuel cap.

Always nice when something simple solves your problem. Update us if things change.