P0302: Cylinder 2 Misfire Detected

What Is P0302?

P0302 is a generic diagnostic trouble code (DTC), defined as “Cylinder 2 Misfire Detected.” Your vehicle’s powertrain control module (PCM) registers this code on misfire detection in engine cylinder 2. 

What’s a misfire? 

An engine misfire is when the combustion in an engine cylinder doesn’t execute correctly. As a result, that cylinder doesn’t produce power and releases unburned fuel.

NOTE: Cars typically have 4, 6, or 8-cylinder engines. Here, the number 2 cylinder refers to the cylinder numbered “2” in the engine’s cylinder arrangement. 

Code P0302 is part of a series of cylinder misfire DTCs ranging from P0300 to P0012. Each code in this series indicates a misfire detection on a particular cylinder. For instance, code P0301 means misfire on cylinder #1, whereas P0308 indicates misfire on cylinder #8. 

How Does the PCM Detect a Misfire in Cylinder #2?

The Powertrain Control Module (PCM) continuously tracks the crankshaft’s rotational speed, which should remain consistent during normal operation. A misfire in cylinder #2 causes the crankshaft to momentarily slow down during the combustion cycle for that cylinder. 

Even a single cylinder misfire can result in a slight drop in RPM, which the PCM records as a potential irregularity. When misfires in cylinder #2 have occurred frequently within the last 200 revolutions of the crankshaft (and the catalyst temperature has been more than 1,000°C), the PCM identifies a pattern and sets the P0302 code. The PCM activates the Check Engine Light  (CEL) to alert the driver of the issue.

Certain vehicles are more prone to experiencing the P0302 code due to design or configuration factors. Popular brands like Ford, Toyota, Dodge, Chevy, and Honda Motor Company are among those where this automotive issue is commonly reported.

Common Causes for P0302 Trouble Code

Several factors can lead to a cylinder 2 misfire, causing your Check Engine Light to come on. 

The most common ones for code P0302 are:

A. Ignition System Issues 

• Worn or damaged spark plugs 
• Faulty spark plug wire or connector
• Failing or damaged ignition coil 
• Faulty ignition coil connector
• Distributor failure or damaged distributor cap
• Distributor rotor button damage

B. Fuel Delivery Problem

• Faulty cylinder 2 injector or injector connector
• Low fuel pressure
• Old or contaminated fuel

C. Sensor Malfunctions 

• Defective crankshaft sensor (crankshaft position sensor)
• Bad camshaft position sensor
• Faulty mass airflow sensor
• Bad oxygen sensor (O2 sensor)
• Damaged throttle position sensor (located on the throttle body)

C. Mechanical Problem

• Vacuum leaks
• Engine timing is off
• Leaking head gasket
• Low engine compression
• Burned or sticking valve
• Worn or weak piston rings
• Valve cover gasket damage

D. Others

• Clogged EGR valve or tube
• A faulty or damaged catalytic converter
• A defective powertrain control module

NOTE: If another misfire code accompanies the P0302 code, there’ll likely be more than one potential cause.

9 Most Common Symptoms of Code P0302

If your powertrain control module has registered the P0302 trouble code, your vehicle may experience: 

1. A flashing Check Engine Light
2. Rough idle that becomes more pronounced during deceleration
3. Engine hesitation or stalling 
4. Low engine speed
5. Difficulty starting the engine
6. Reduced engine performance
7. Foul odor or black smoke from the exhaust (due to unburned fuel)
8. Decrease in engine power (especially while accelerating)
9. Excessive fuel consumption due to an affected fuel mixture

Is P0302 Trouble Code Serious?

Yes, code P0302 is a serious code and should not be ignored. 

If a misfire code is left unaddressed, it could affect your engine efficiency and can even lead to ignition failure or catalytic converter damage, which is a costly repair. It also makes driving highly unsafe. Your vehicle may stop abruptly, leaving you stranded on the road.

Furthermore, a misfiring cylinder can negatively impact your fuel economy and prevent your vehicle from meeting the emission standard. 

So, if your Check Engine Light begins flashing due to the P0302 code, stop driving immediately to avoid further engine damage. 

How to Diagnose P0302 Misfire Code

Multiple reasons could trigger a code P0302, including damaged spark plugs, a bad ignition coil, or a defective fuel injector. Hence, it’s very common to misdiagnose this code as a fuel injector, oxygen sensor, or PCM issue. 

To avoid unnecessary DIY repairs and ensure correct troubleshooting for the error code, it’s best to opt for a professional diagnosis. 

Here’s how a certified technician will identify the root cause of a misfiring cylinder and P0302 engine code:

1. Use an OBD-II scan tool or code reader to check for additional error codes and fix them first if found. For example, code P0300 indicates multiple or random misfires occurring in more than one cylinder.

2. Perform a visual check on the ignition coil for loose connectors and damaged wiring. Secure engine ground wires.

3. Do a visual check for cylinder 2 to identify a faulty spark plug and inspect the wire for wear or carbon build-up. Then, test the spark plug wire resistance using a multimeter.

4. If your vehicle uses an ignition coil pack, swap the coil from cylinder 2 to another cylinder. Clear the code, test drive, and see if the misfire moves to the other cylinder.

5. Check for low fuel pressure caused by issues like a faulty fuel pump, cylinder 2 injector, fuel injector connector, or fuel pressure regulator.

6. Inspect different sensors for faults; this includes the crankshaft position sensor, camshaft position sensor, mass airflow sensor, etc.

7. Perform a leak-down and compression test to identify any mechanical problem, such as vacuum leaks, a broken valve, or a worn cylinder head.
   These could lead to low compression pressure in the combustion chamber.

8. If the problem persists, check the powertrain control module for potential faults.

Possible Repairs and Costs for P0302

While P0302 is a generic powertrain trouble code, the repair steps could vary according to your specific vehicle. 

Potential solutions include:

• Replacing a faulty spark plug set
• Installing a new ignition coil pack or replacing the ignition coil connector
• Installing a new O2 sensor or crankshaft sensor
• Addressing fuel injector issues
• Repairing mechanical problems, like a vacuum leak in the intake manifold or damaged valve cover gasket, to fix low compression

Repair Costs for P0302

A mechanic may charge a flat diagnostic fee of $75-$150 to figure out the root causes.

Here are the estimated costs of repairs or replacements they may suggest:

• Spark plug replacement: $50-$750 for a set
• Vacuum leak repair: $100-$1500
• Spark plug wire replacement: $220-$605 for a set
• Ignition coil replacement: $85-$470
• Fuel pressure regulator replacement: $260-$870
• Fuel pump replacement: $1100-$1,300
• Powertrain control module replacement: $1050-$1,100
• Fuel injector replacement: $335-$2,000
• Distributor rotor and cap replacement: $190-$305
• Valve cover gasket replacement: $110-$380

How to Prevent Misfires in the Future: Practical Tips

Here are a few proactive steps you can take to prevent engine misfiring:

• Routine checks of the spark plug set, ignition coils, and fuel pressure can catch potential issues early.
• Always use high-quality replacement parts to ensure durability and performance.
• Avoiding aggressive driving can reduce wear on engine components, potentially extending their lifespan.

That said, winter conditions often exacerbate the problem. Cold temperatures and damp environments add stress to critical engine components, increasing the likelihood of seeing a P0302 code.

You can follow these tips to keep your car running smoothly during winter: 

• Replace worn spark plugs, inspect ignition coils, and test the battery before the onset of winter.
• Fill up with winter-grade fuel to ensure better combustion.
• Use a block heater or park in a garage to keep the engine and fuel system warmer.
• Add fuel system cleaners to prevent injector clogs and stabilize the fuel.