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56 Posts
Discussion Starter · #1 ·
So I was driving along on my lunch break, hit some boost in 3rd gear high load. I then go to slow down for some traffic and lose power breaks. and car stalls when I do come to a stop. Now at idle the rpms will sure and go to 2-4k rpms and drop down. Then after a minute or so of that it might stall. It also is bucking a bit and will stall out if I dont keep rpms up.

I pulled codes P1300 and P0300 and I had to drive it back to work without power breaks. Does this sound like a brake boost issue? Or is this the DIC? What is the DTC that code p1300 mentions?

10,049 Posts
P1300 & P0300 for Your application:
Market US/CA:
CHECK ENGINE. Running unevenly and misfiring.

Random Misfire Detected.

Fault symptoms


• Running unevenly and misfiring.

On-Board Diagnostics
Type of diagnosis:

- Continuous. But interrupted when fault criteria fulfilled and will not restart until next driving cycle.

Enable criteria:

- General conditions for this trouble code: Atmospheric pressure must exceed 72 kPa and the engine coolant and intake air temperature must exceed -7°C.

- Engine running. Main relay voltage exceeding 10V. Ignition discharge module combustion signals registering. The number of missing combustion signals is accumulated for each cylinder every 1000 engine revolutions. The total number of accepted misfires during 1000 engine revolutions is specified in a load and engine speed-dependent matrix.

Fault criteria:

- Number of missing combustions exceeding number of accepted misfires.


- P1312 and P1334.

System reaction to a fault:

- Under high engine loads, closed loop will be blocked while misfiring occurs.

OK report:

- Provided fault criteria are not fulfilled during the driving cycle, the OK report will made when the ignition is turned off and before the engine stops.

Two other types of OK report can also be made:
Type 1: If a diagnostic trouble code has already been stored for the diagnosis and the same running conditions have occurred (coolant temperature above or below 71°C, engine speed ±375 rpm and load ±10%).
Type 2: If there is no diagnostic trouble code stored for the diagnosis or the same running conditions have not occurred.

Fault handling: (For more information, see .)

- Type II.

Diagnostic help
If any other trouble codes have been generated, check whether fault diagnosis should be started on any of them first. Read Freeze Frame and change spark plugs.

Then make a general inspection of connectors and hoses and subsequently a thorough check of compression, ignition and fuel system.

Functions in the diagnostic tool related to the fault:

• Diagnostic status for the diagnosis.

• Misfire Cyl 1.

• Misfire Cyl 2.

• Misfire Cyl 3.

• Misfire Cyl 4.

• Multiplicative Adaptation, unit %

• Additive adaptation, unit mg/c.

• Closed loop, unit %.

• Purge Adaptation, unit %.

• Air mass deviation from calculated, unit %.

• Activating misfire counter reset.

• Activating ignition triggers.

• Activating injector test.

• Activating pump test.

For information, see .

Checking the wiring
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.
Read Freeze Frame and make a note of the following data: Engine RPM Airmass / Combustion Coolant Temperature
Check visually that:
the hose connections are coupled between the compressor and the throttle body
the vacuum hose between the fuel pressure regulator and intake manifold is undamaged.
Check with the diagnostic tool that the coolant temperature sensor indicates a reasonable value. Rectify as necessary.
Check the compression of the cylinders.

56 Posts
Discussion Starter · #4 ·
Soooo.....that means could be wiring harness. Could be spark plugs? It doesnt mention the DIC in there....does that mean odds are its not that? Im trying to figure out how such a big issue could happen all of a sudden. My hoses seem fine also. I did a quick visual.

1,001 Posts
Oh I see the bottom now.....Il have to check that stuff. Big vacuum leak sounds like it could be the culprit. But to cause me to loose my power brakes?
Brake booster for power brakes requires vacuum. I'd check your vacuum lines, as stalling/rough running is a good sign, but losing power breaks leads me to believe maybe the booster went bad, or the hose to it is cracked.

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