Replace fuel regulator
I just fixed this gremlin after a long time and it turned out to be the m.a.p. sensor, manifold absolute pressure sensor.
problem was with a 2004 saab 9-3 with the 2.0. Along with the code came gasoline leaking down into the oil in crankcase. It was actually not the sensor itself but a broken wire in the plug to the sensor. In my case, it was the far left wire facing engine bay, though i don't know what that particular wire does exactly. My theory is that the failure of connection in that wire caused a very rich air-fuel mixture. With a new pigtail (or plug to sensor with wires), the car is a lot quicker now, and no more code p0300!
How are your rear lights. Are they dim. Check the trunk ground if you have any rust issues. Any issues with it backing up and it stops running. Bad ground. Had this issues. Reconnected ground and ran great. You may have a bad spark ignition module or some other issue.
Number of possible causes.
this is worth a look:
https://www.700r4transmissionhq.com/p0300-saab-9-3/
given the age of the car, I'd be looking at the simple things first.
vaccum leaks. Hoses degrade, split etc... so if you've got access to a small regulated cylinder of propane, try sniffing out all the vac hoses, throttle body connections, inlet hose, MAP and MAF connection etc. Before you start pulling things to pieces.
loss of vac affects fuel trims (check out YouTube Schrodingers box) for some really good info about that.
plenty of other vids on you tube etc Eric the car guy, ratchetsnwrenches etc
have you looked at the MAF ? Cleaned it ? Don't be tempted to use brake cleaner or carb cleaner though...use a proper specially formulated MAF cleaner.
other basics are plugs...correct plugs , properly gapped and in good condition ? Check out spark plug diagnosis, loads of stuff on the net about that
Saab 9 3 P0300 Engine Misfire Detected Drivetrain...
P0300 is one of the most common...
SOURCE: diagnostic codes for 200 Daewoo Lanos..........
Do you feel a misfire?? Random misfires are usually caused by a lean fuel mixture, the reasons that cause this a to many to list here.
SOURCE: Tacoma 4cyl idles rough, heditates, multiple misfires
Possible fuel delivery problem, fuel pump, fuel line, clogged fuel filter, leaking injectors or injector O-rings, faulty pressure regulator etc. Check your fuel pressure.
SOURCE: setting code P0300- random multiple
This could be any number of problems in your spark system but most likely your control module for your spark plug coils.
SOURCE: get multiple misfire codes. P0300 - P0303. If this
This could be a coil problem but i would start by changeing the plug wires and checking each plug.
SOURCE: 2004 saab 9-3 turbo won't accelerate
hopefully it doesn't end there.
i had the same issue, fixed it for the same amount of money (i own a 2004 9-3).
then the turbo went out again. took it in for repairs and they replaced the turbo gasket for about $800. car briefly worked.
then took it in for 60,000k tuneup which cost about $1000 and didn't really impact the way the car felt, but oh well...
now the acceleration has gone out again and they are telling me i have replace the whole turbo system to the tune of $2000 .
my saab is slowly and steadily starting to let me down...
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