AutoCodesHonda – P0303 Honda

P0303 Honda Code - No. 3 Cylinder Misfire Detected

Quick Answer

The crankshaft vibrates slightly when each cylinder fires. Common causes include Valve adjustment, Faulty spark plug #3, Faulty ignition coil #3. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0303 Honda indicates No. 3 Cylinder Misfire Detected.
Common causes
Common causes include Valve adjustment, Faulty spark plug #3, Faulty ignition coil #3.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code Popularity 109,807
How popular is this code, among other codes? Medium
Table of contents Created and updated by William Orellana on Aug 16, 2023
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Code P0303 Honda Description

The crankshaft vibrates slightly when each cylinder fires. If a misfire occurs, the crankshaft rotation speed changes rapidly. The Powertrain Control Module (PCM) monitors the crankshaft rotation speed based on the output pulses from the Crankshaft Position (CKP) Sensor. By monitoring changes in the crankshaft rotation speed, the PCM counts the number of misfires and determines which cylinder is misfiring. If a misfire is detected, a Diagnostic Trouble Code (DTC) is stored.
There are two types of misfire detection: Type 1: When the number of misfires per 200 engine revolutions reaches the level that can damage the three-way catalyst (TWC), a DTC is stored and the MIL blinks. Type 2: When the number of misfires per 1,000 engine revolutions reaches the level that affects exhaust emissions but is not severe enough to immediately damage the catalyst, a DTC is stored, and the MIL comes on.
OBDII Code P0303 Honda - No. 3 Cylinder Misfire Detected - AutoCodes.com
P0303 Honda Code - No. 3 Cylinder Misfire Detected

What are the Possible Causes of the DTC P0303 Honda?

  • Valve adjustment
  • Faulty spark plug #3
  • Faulty ignition coil #3
  • Clogged or faulty fuel injector #3
  • Intake air leak
  • Insufficient cylinder #3 compression
  • Incorrect fuel pressure

How to Fix the DTC P0303 Honda?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

Code Tech Notes

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0303 Honda code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0303 Honda code?

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Information for Specific Honda Models

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0303 Honda Code

No Frequently Asked Questions about P0303 Honda Code found.

Discuss the causes and fixes for P0303 Honda OBDII Code

  • I have a 2002 Honda Accord that has a misfire on cylinder three I've replaced the plug wires the spark plugs the distributor cap and rotor button and the engine is still running rough and I still have a code saying it's a misfire on cylinder three

  • Try to do all valves adjustment.

  • You next step is to perform a cylinder head valve adjustment. Usually the valve adjustment takes care of the problem.

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