P0303 Cylinder #3 Misfire

Description and meaning of DTC p0303

This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model. A P0303 code means that the the car's computer has detectedthat one of the engine's cylinders is not firing properly. In this case it'scylinder#3.

p0303 diagnostic trouble code symptoms

Symptoms may include:the engine may be harder to startthe engine may stumble / stumble, and/or hesitateother symptoms may also be present

DTC p0303 - possible causes

A code P0303 may mean that one or more of the following has happened:Faulty spark plug or wireFaulty coil (pack)Faulty oxygen sensor(s)Faulty fuel injectorBurned exhaust valveFaulty catalytic converter(s)Running out of fuelPoor compressionDefective computer

How to fix OBD-II diagnostic trouble code p0303

If there are no symptoms, the simplest thing to do is to reset the code andsee if it comes back. If there are symptoms such as the engine is stumbling or hesitating, checkall wiring and connectors that lead to the cylinders (i. e. spark plugs). Dependingon how long the ignition components have been in the car, it may be a goodidea to replace them as part of your regular maintenance schedule. I wouldsuggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a. k. a. coil packs). In some cases, the catalyticconverter has gone bad. If you smell rotten eggs in the exhaust, your cat converterneeds to be replaced. I've also heard in other cases the problems were faultyfuel injectors.

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