P0300 on Saab: How to Diagnose & Fix
Random/Multiple Cylinder Misfire Detected
2 Saab models · 3 documented issues · 3 critical · $80-$600 repair
P0300 on Saab by model: symptoms, diagnosis and fix
NHTSA campaigns 05V399 and 06V410 together cover specified 2001-2003 Saab 9-5 V6 vehicles with B308 gasoline engines. The campaign documents describe an ignition-discharge-module IGBT that can overheat and burn out, stalling the engine and increasing crash risk; 06V410 expanded the V6 population. Whether a car is covered, whether the campaign was completed and which module version is installed all depend on the VIN; symptoms alone cannot tell you.
Common Symptoms
- Engine stall or no-start
- Ignition-related trouble code
How to Fix
Check the VIN for open campaigns 05V399 and 06V410 and have the authorized recall inspection or module replacement completed if applicable. For a stall, no-start or ignition DTC on a vehicle with completed campaigns, diagnose module power, wiring, engine management and other causes using WIS before replacing parts. Do not buy an ignition discharge module from this page; VIN campaign status, B308 application, bank, installed module and diagnosis determine the remedy.
Sources for this issue (3)
The Direct Ignition Cassette, which sits directly on top of the spark plugs and combines the coils into one unit, is a frequent failure point on the four-cylinder cars. Underhood heat and valve-cover gasket oil leaks contaminating the coil pack degrade the cassette over time, causing misfires, rough idle, hard starting and stalling. A failed cassette typically has a burnt smell and discoloration around the plug boots.
Common Symptoms
- Engine misfire
- Rough idle
- Hard starting / crank no-start
- Stalling while driving
- Check engine light
- Burnt smell from engine bay
How to Fix
Replace the Direct Ignition Cassette (use a quality OEM-grade unit) and renew the spark plugs at the same time, using the correct Saab-specified plugs and dielectric grease. Fixing any valve-cover gasket leak prevents repeat failures.
Sources for this issue (3)
The Saab Direct Ignition Cassette — single integrated unit covering all four spark plugs — is a well-known wear item on the first-generation 9-3 (1999-2003, B204/B205/B235 engines) and the 9-5; the 2003+ second-generation 9-3 with the B207 uses separate ignition coils instead. Symptoms: misfire (often cylinder-specific then random), reduced power, check engine light. Failure rate climbs sharply after 80,000 miles. Saab DIC heat-shielding cracks; rubber boots fail.
Common Symptoms
- misfire
- reduced power
- check engine light
- no-start
- rough idle
How to Fix
Replace DIC ($150-$350 OEM cassette, $80-$180 aftermarket — quality matters here, cheap units fail in months). DIY ~30 minutes with a 10mm hex socket. Always replace spark plugs at the same time with Saab-specified resistor plugs (NGK PFR6H-10 on the B205, B235 and 1999 200 hp B204; NGK BCPR7ES on the 1999 185 hp B204). Carry a spare DIC if traveling long distances — failure is sudden but the car limps home on the remaining cylinders.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Saab Genuine Trionic 7 black direct ignition cassette 32022255 (previous 55559955)
Not B207 Sport Sedan and not red Trionic 5 cassette cars; confirm VIN/engine.
- NGK PFR6H-10 spark plug, Saab 9399866
Confirm engine, tune/heat-range requirements and gap.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (2)
P0300 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0300 mean on a Saab?
P0300 stands for "Random/Multiple Cylinder Misfire Detected." P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. On Saab it is documented across 2 models: 9-5, 9-3.
What are the most common causes of P0300?
The most common causes of P0300 are: Worn or fouled spark plugs (across cylinders), Vacuum or intake air leak, Weak fuel pump, clogged fuel filter, or low fuel pressure, Failing ignition coils or worn spark plug wires, Dirty or faulty mass airflow (MAF) sensor, Clogged or dirty fuel injectors, Faulty crankshaft/camshaft position sensor, Low compression or EGR/PCV system faults. The specific cause varies by vehicle.
How much does it cost to fix P0300 on a Saab?
Published repair estimates on Saab range from $80 to $600 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.