P0303 on Saab: How to Diagnose & Fix
Cylinder 3 Misfire Detected
2 Saab models · 3 documented issues · 3 critical · $80-$600 repair
P0303 on Saab by model: symptoms, diagnosis and fix
The Saab Direct Ignition Cassette — single integrated unit covering all four spark plugs — is a well-known wear item across 9-3 (and 9-5) from 1999 through end of production. 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 (NGK PFR7S8EG or equivalent). 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.
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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, applying the correct Saab dielectric plug. Fixing any valve-cover gasket leak prevents repeat failures.
Sources for this issue (3)
Same DIC failure mode as 9-3 — 1999-2009 9-5 with the B235 2.3L turbo (Linear/Arc/Vector NA variants are B205) suffers DIC degradation. Saab dealers used to stock these by the dozen. Often the first part to fail on a high-mileage 9-5.
Common Symptoms
- misfire
- reduced power
- rough idle
- check engine light
How to Fix
Replacement DIC ($150-$350 OEM, $80-$180 aftermarket). NGK PFR7S8EG plugs at the same time. Trionic 7 ECU on 1999+ models compensates for misfire well, so the car often limps home — but P03xx codes will accumulate. Some owners pre-emptively replace at 100,000 miles.
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)
First-generation Saab 9-5 B205/B235 four-cylinder Trionic 7 only; 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.
P0303 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 P0303 mean on a Saab?
P0303 stands for "Cylinder 3 Misfire Detected." This code means your engine's computer detected a misfire specifically in cylinder number 3 — that cylinder isn't burning its fuel-air mixture properly or completely. The computer senses misfires by watching for tiny fluctuations in crankshaft speed each time a cylinder is supposed to fire. A misfire wastes fuel, can cause a noticeable shake, rough idle or loss of power, and can flood raw fuel into the exhaust where it may overheat and damage the catalytic converter. Because the fault is isolated to one cylinder, the cause is usually something specific to that cylinder's ignition, fuel delivery, or compression. On Saab it is documented across 2 models: 9-3, 9-5.
What are the most common causes of P0303?
The most common causes of P0303 are: Worn or fouled spark plug in cylinder 3, Failed or weak ignition coil on cylinder 3, Bad spark plug wire or boot (where applicable), Clogged or leaking fuel injector for cylinder 3, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/leaking valve, head gasket), Wiring or connector fault at the coil or injector. The specific cause varies by vehicle.
How much does it cost to fix P0303 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.
Looking for P0303 on a different make?
View P0303 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.