Error P0303 – how to fix?

Hi-ya!,at this moment. In this post you will see a description of fuses and relays Error P0303 – how to fix?

Include with pictures of block diagrams along with their locations. Highlighted the cigarette lighter fuse (as the most used thing people look for).
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P0303 Code Definition

P0303 is a generic diagnostic trouble code (DTC) that indicates a problem with cylinder 3 ignition. This code may be seen with other misfire codes as well as Lean / Poor codes.

What does the code P0303 mean

DTC P0303 Will Set When the ECU detects a multiple cylinder 3 misfire. A misfire misfire causes the ECU to turn on the Check Engine light and put the vehicle into Fail Safe mode to prevent damage. The Check Engine light will remain on until the code is cleared.

What causes the code P0303?

  • Faulty spark plugs
  • Fuel injection problems
  • Problems with spark plug leads, hubcap and rotor or coil pack (depending on what the vehicle is equipped with).
  • Mechanical problems of the engine
  • Intake air leaks

What are the symptoms of the P0303 code?

P0303 has various symptoms. In some cases, the driver may only notice the check lamp of the engine and no other symptoms. In other cars, the vehicle may run poorly, have misfiring, stalling, hard starting and fuel economy problems.

How can a mechanic diagnose the P0303 code?

  • There are many different systems that cause the P0303 code so it’s important to follow all the steps in the correct order:
  • The mechanic will connect a scanning tool to check for any current, historical or pending codes.
  • After that, all data from the frozen frames will be saved for use during a test drive.
  • All codes will be cleared and a test drive will be carried out.
  • A visual inspection will now be performed for wear, damaged components, leaks and damaged wiring.
  • The scan tool will be used to check the misfire count for cylinder # 3 while it is running.
  • Long term fuel trimmers will be checked to verify that there are any fuel or intake problems.
  • In some cases, spark plugs can be removed and inspected.

The most common errors when diagnosing the code P0303

As with any diagnosis, follow all steps to avoid mistakes that waste time and money. The most common mistake is to overlook fuel problems or a leak in the air intake as the cause of the misfire. While spark plugs themselves are the most common cause, they are not the only cause of P0303.

How serious is the P0303 code?

P0303 can cause driving symptoms such as a lack of power or an engine misfire which can be discomfort while driving. In these cases, the P0303 code should not prevent you from reaching a safe location. Once your vehicle is in a safe place, it can be diagnosed and repaired quickly.

What repairs can remove the P0303 code?

The repairs for P0303 are listed in order of most likely to least likely:

  1. Replace spark plugs in all cylinders.
  2. Replace cap and impeller, coil pack or spark plug wires as needed
  3. Repair of intake air leaks
  4. Repair fuel problems
  5. Repair of mechanical problems of the engine

Additional notes regarding code P0303

A scan tool that can view live engine data from sensors is very important when diagnosing P0303. This allows technicians to view long-term fuel trims, intake air sensor readings, fuel injector performance, and cylinder misfire counters. All this data is used to determine which chip is causing P0303.

Spark plugs are normally replaced at the intervals specified by the vehicle manufacturer. They do not last for the life of the vehicle and are one of the most common causes of misfire in vehicles, especially those with higher mileage. If the vehicle is equipped with a distributor with a hubcap and rotor system, they must be replaced at regular intervals as these are mechanical parts that wear out over time. On vehicles with spark plug wires, the wires are usually replaced when the spark plugs are made because engine heat causes the wires to fail over time.

Newer vehicles can be equipped with a coil package. They generally last longer than the spark plug leads or the cap and impeller. When the coil packs fail, their diagnosis may be slightly different. The easiest way is to transfer the suspect coil pack to another cylinder; if the misfire changes to a new cylinder, the coil pack is the cause. Coil packages are usually listed as a complete set.

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