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Fault code P0303 means misfires on cylinder 3. Irregular combustion localised on the third cylinder.

Typical symptoms

• Engine shaking at idle
• Loss of power
• Engine light on or flashing

Most common causes

• Cylinder 3 spark plug or coil
• Clogged injector
• Loss of compression
• Damaged wiring

How it is checked in diagnosis

• Swapping components between cylinders to isolate the fault
• Compression test
• Checking the corrections per cylinder

Can you drive with code P0303?

With a flashing light no: reduce speed and have the car checked.

How MasterTuning helps

We read the real values from the ECU, not just the code: that is the difference between identifying the component responsible and replacing parts by trial and error. After the repair we clear the fault and check that it does not come back. Centres throughout Italy.

Read more: vehicle database · find an installer · what is ECU remapping

Do you have code P0303 on your car? Book a diagnosis at your nearest MasterTuning centre.

Frequently asked questions

What does fault code P0303 mean?

Code P0303 means misfires on cylinder 3. Irregular combustion localised on the third cylinder.

Can you drive with fault P0303?

With a flashing light no: reduce speed and have the car checked.

Is clearing code P0303 enough to fix it?

No: if the cause is still present the code comes back after a few kilometres. Clearing should only be done after the repair, with the diagnostic tool.

How much does it cost to fix code P0303?

It depends on the component responsible: the diagnosis is precisely what identifies it with real measurements, avoiding unnecessary replacements that cost far more than the correct repair.