P0303

TORQDEX // POWERTRAIN DTC

Cylinder 3 Misfire Detected

Misfire activity has been detected repeatedly on cylinder 3.

CODE FAMILY Powertrain
SEVERITY HIGH
DRIVEABILITY May Be Limited
COMMON AREA Cylinder 3 / Ignition / Fuel / Mechanical

01 // CODE DEFINITION

What P0303 means

P0303 identifies a combustion problem occurring on cylinder 3.

The fault can originate from ignition, fuel delivery, compression, air leakage, wiring, or mechanical condition.

02 // COMMON SYMPTOMS

What you may notice

Rough idle
Engine vibration
Hesitation
Reduced power
Flashing check-engine light

03 // COMMON CAUSES

What can trigger P0303?

IGNITION

Ignition fault

A weak plug, coil, wire, or electrical connection may cause the misfire.

FUEL

Injector fault

Cylinder 3 may not be receiving the proper amount of fuel.

MECHANICAL

Mechanical fault

Low compression or valve-train problems may affect combustion.

04 // DIAGNOSTIC ORDER

Start here

01

Verify the affected cylinder

Review live misfire counters when available.

02

Check ignition components

Inspect and swap appropriate components to see whether the fault moves.

03

Check injector operation

Verify electrical and mechanical injector performance.

04

Check mechanical condition

Perform compression or leak-down testing if needed.

05 // DIAGNOSTIC PRINCIPLE

Confirm the fault before replacing parts

P0303 identifies a condition detected by the vehicle control system. It does not automatically identify one failed component. Test the affected system before replacing parts.