P0302 Code

What Is a P0302 Code?

Most vehicles are equipped with onboard diagnostics (OBD) systems that alert you when an issue arises. While it might be alarming to see the engine light illuminate, you can get to the bottom of the problem by connecting a scanner to the vehicle’s OBD system. The scan tool will allow you to view the diagnostic trouble code (DTC), which is significantly helpful in pinpointing the problem.

If a P0302 engine code appears, it usually indicates an issue with your engine’s cylinder — specifically, a misfire on cylinder 2.  

What Does the P0302 Code Mean?

The P0302 code is a critical diagnostic code that means a misfire was detected on cylinder 2. Identifying these problems is crucial since the cylinder’s chamber is where fuel combusts and produces power. A misfire usually occurs when combustion is interrupted or does not take place.

The powertrain control module (PCM) controls and monitors a cylinder’s operation. Equipped with several sensors, the PCM can detect when issues with cylinders occur. This device specifically monitors the engine speed and crankshaft position, which slow down every time a particular cylinder misfires. When this issue occurs, the PCM sends the P0302 error code to notify you. 

Today’s vehicles have multicylinder engines that, on average, have four to eight cylinders. As such, it’s important to note that cylinder 2 refers to the specific number on the cylinder, not its position in the firing order. 


Potential Causes of the P0302 Code

While a P0302 engine code notifies you of a cylinder 2 misfire where combustion was continually interrupted or didn’t occur, it does not provide the direct cause of the issue. However, the error code does narrow down the problem and serves as a guide for where you can begin diagnostics. Some of the potential causes for a cylinder 2 misfire include: 

  • Faulty, unclean or unclogged fuel injectors
  • Damaged injector circuits
  • Spark plug failure
  • Low compression
  • Spark plug wire failure
  • Leaking head gaskets
  • Failed coil packs
  • Damaged or burnt valves 
  • Faulty ignition
  • Problems with the PCM and engine speed sensor 


Common Symptoms of the P0302 Code

The check engine light is one of the most direct ways that a vehicle alerts to a PO3O2 code. However, you may notice a few other signs of trouble that you can trace back to the P0302 engine code. Demanding conditions such as driving uphill or towing can make the issues even more noticeable. Here are several common symptoms of a P0302 code to look for:

  • Stalling 
  • Poor engine performance 
  • Rough or choppy engine feeling
  • Difficulty starting the engine 
  • Decreased engine power 
  • Extended cranking
  • Rough or erratic idling
  • Unusual odor coming from the engine or exhaust
  • Excessive fuel consumption


Why You Should Not Ignore a Cylinder 2 Misfire

A P0302 code or cylinder 2 misfire can vary in severity. Some situations cause minor drivability issues, while others are more serious. Regardless of the problem’s seriousness, it’s crucial to address it promptly before causing further damage. 

Ignoring a P0302 engine code and leaving the problem unaddressed can lead to increased fuel consumption, lower power output and damage to other engine components.  


Steps for Diagnosing the P0302 Code

When diagnosing a P0302 engine code, it’s important to remember that a range of issues with fuel delivery, ignition systems and engine mechanical components could be the cause. The diagnosis will require a comprehensive assessment of various parts to determine which one is behind the cylinder misfire. Here are some of the common steps involved:  

  • Check for other codes: Check for other DTC codes that may accompany the cylinder 2 misfire. If other codes are present, there might be an issue that affects other cylinders. However, if the P0302 code is the only one that appears on the scanner, then you can focus on diagnosing a problem with cylinder 2. 
  • Inspect the spark plug: Spark plugs can fail over time due to wear and tear, a leaking fuel injector or excess fuel. Carefully inspect the spark plugs, as well as the spark plug boot, wires and connectors, for any signs of failure. 
  • Check the ignition coil pack: You can test whether the ignition coil pack is malfunctioning by swapping it with an adjacent cylinder. If the swapped cylinder misfires, the ignition coil pack is the issue. 
  • Examine the fuel injectors: Ensure that the fuel injectors are clean, free of debris and functioning properly. Faulty fuel injectors can disrupt the fuel delivery to cylinder 2 and cause a misfire.   
  • Assess the cylinder compression: A compression test can also be conducted as part of the diagnostic process. Low compression can be caused by various issues, including worn cylinder gaskets, valves or pistons.

While some of these assessments are easy to tackle for seasoned do-it-yourselfers, consider letting a professional handle the job. A trusted mechanic can determine the extent of the P0302 issue and suggest or conduct the necessary repairs.  


How to Fix the P0302 Code

The process of fixing a P0302 code depends on what you uncover during the diagnosis. Once you pinpoint the cause of the issues, you can begin repairs or make the necessary replacements. Some of the most common fixes for a P0302 code include: 

  • Replacing spark plugs 
  • Replacing the ignition coil pack
  • Cleaning or replacing fuel injectors 
  • Replacing faulty components like valve cover gaskets 
  • Replacing the cylinder head gasket


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