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How to Fix a P0302 Code – Causes, Symptoms and Cost

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P0302 code means “Cylinder 2 Misfire Detected”. This can happen for various reasons, and a mechanic will need to figure out what caused the code to be activated in your case.

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A motorist is sure to have their fair share of car problems during their lifetime. A check engine light conjures up images of costly repairs and car downtime for most drivers. As a result, many people start to worry. 

On the other hand, a check engine light frequently indicates a minor operational fault that should be addressed ASAP! The check engine light comes on when an engine’s control module stores a diagnostic issue code. These DTCs (diagnostic trouble codes) are extremely prevalent, especially as a car gets older. P0302 is one such DTC.

Continue reading to discover more about DTC P0302 and how to resolve the code’s root cause if it occurs.

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P0302 – What does it mean?

Most cars have four or six cylinders. One by one, each cylinder fires a spark plug. In addition, each cylinder has a spark plug on top of it. The spark plug produces energy by igniting the combustible air/fuel mixture with an electric spark.

All of the cylinders working together control the crankshaft’s rotation. As a result, the crankshaft can rotate continuously when each cylinder fires. This procedure is responsible for the cars’ smooth operation. If a cylinder misfires, the crankshaft revolutions per minute (RPM) may increase or decrease. The powertrain control module will store a fault code if the percentage of increase or decrease is more than 2%.

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The Check Engine Light will illuminate if the crankshaft rotations per minute have increased or decreased by 2% to 10%. Likewise, the Check Engine Light will flash if the crankshaft revolutions per minute have risen or reduced by 10%. A blinking Check Engine Light signals a more significant problem with misfiring. The P0302 error code indicates that cylinder two is misfiring and not receiving enough spark to its spark plug.

What to look for when you see P0302

The symptoms associated with the commencement of a P0302 DTC are not the same for every engine. However, several driveability-related symptoms can appear when a misfire code of this sort is present.

Some of the most prevalent symptoms associated with code P0302 are listed below:

  • No start/hard start situation
  • Stuttering under load
  • Power outage
  • Lose in Mileage
  • Stalling occasionally

What causes Code P0302?

What causes Code P0302?

Several different things can cause a P0302 problem code. Electrical or emissions system failure can potentially cause a P0302 DTC to appear in some situations. The causes of code P0302 are listed below:

  • Spark plug failure
  • Spark plug wire failure
  • The coil pack is not working.
  • The fuel injector is faulty, unclean, or clogged
  • Cylinder compression is low.
  • Excessive rotor button wear and tear
  • Engine speed sensor (crankshaft/camshaft) failure
  • Valve damaged or burnt
  • The head gasket is leaking.
  • Vacuum leaks
  • EGR valve malfunction 
  • Plugged EGR passages
  • Catalytic converter clogged
  • PCM (powertrain control module) failure

What causes cylinder 2 to misfire?

A misfire is usually caused by a bad spark plug or another problem with the spark system. It could also be caused by: a problem with how the fuel gets to the engine. Other issues could be a technical problem with the engine or the exhaust gas being recycled.

How serious is code P0302?

The underlying reason for a misfire code should be identified, diagnosed, and corrected ASAP. For example, engine efficiency is harmed when a misfiring engine has less than ideal combustion on one or more cylinders.

As a result, various drivability concerns can occur, perhaps leaving a driver stranded in the worst-case scenario. The most serious issue caused by an unresolved misfire DTC is the possibility of damage to a car’s catalytic converter.

Superheating a catalytic convertor’s core structure can occur as unburned fuel is delivered downstream through a car’s exhaust system. Basically, this usually leads to premature catalytic converter failure over time.

How serious is code P0302?

Steps to fix P0302

To diagnose and repair P0302-related problems, follow the instructions below:

#1 – Examine the components of the ignition system

The failure of ignition system components is the leading cause of P0302 diagnostic trouble codes. As a result, one should begin diagnosing such a problem by thoroughly evaluating all relevant components. Begin by inspecting the engine’s number #2 spark plug for any damage or an incorrect gap. Next, inspect the spark plug wire corresponding to cylinder #2 for damage or chafing.

#2 – Verify the Spark

An inline spark tester can verify the spark on the problematic engine’s #2 cylinder, assuming no visual defects were discovered during your previous visual inspection.

#3 – Verify Fuel Injector Function

Fuel rail pressures can be measured when each engine’s injector is activated using a scan tool with the ignition turned on. If there is no drop in fuel pressure when injector #2 is actuated, more fuel injector diagnostics should be performed to rule out underlying electrical faults.

#4 – Look for any further error codes

If your engine’s P0302 fault code has not been resolved, you should undertake extra tests to confirm that no other DTCs are present. All relevant live-streaming data should be examined to rule out probable sensor-related errors.

#5: Conduct a Compression Test

If your car’s P0302 fault code persists, each engine’s cylinders should be checked for compression. Further diagnostics of a vehicle’s PCM (powertrain control module) will be required if these values are constant across all cylinders, within 10% -15%. 

Consult your car’s manufacturer’s factory-specific service documentation for a final diagnosis.

What is the cost of fixing the P0302 code?

What is the cost of fixing the P0302 code?

It’s impossible to provide a precise estimate without adequately assessing the problem.

Most shops will start with an hour of “diag time” if you bring your car in for a diagnosis (the time spent in labor diagnosing your specific issue). This can cost anywhere from $75 to $150, depending on the shop’s labor rate. If you have the shop conduct the repairs for you, they will apply this diagnosis cost to any required repairs. After that, a shop will be able to provide you with an accurate repair cost for your P0302 code.

Accordingly, the P0302 code may require one or more of the following repairs to resolve the underlying issue if properly detected. These prices include components and labor and are based on national averages. Your pricing will vary depending on your location and car type.

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