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 when it detects a misfire in engine cylinder 2. 

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. 

A. What Does Combustion Do?

Your vehicle moves when the gasoline is burned inside the engine cylinder. Fuel is sent to each cylinder via a fuel injector. A spark is then delivered from the ignition coil to the spark plug, igniting the air-fuel mixture in the cylinder.

The resulting power from the combustion process pushes the cylinder piston, stimulating crankshaft revolutions. The force of the crankshaft revolutions is transferred to your vehicle’s transmission system. Your gear transmission then applies this force to the drive wheels. 

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

The PCM monitors the crankshaft speed and will note any engine speed loss caused by a misfire. 

Occasional misfires occur due to incomplete combustion when the timing of the ignition system is off. But when multiple misfires occur on the #2 cylinder, your PCM registers the P0302 code and activates the Check Engine Light on your vehicle’s dashboard. 

Note: Cars typically have 4, 6, or 8-cylinder engines. Here, cylinder #2 doesn’t refer to the second cylinder in the firing order but is the cylinder numbered as “2” in your engine. 

Some popular auto brands that experience the DTC P0302 code include Toyota, Dodge, Hyundai, and Honda Motor Company.

Common Symptoms

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

• A flashing Check Engine Light
• Rough idle 
• Low engine speed
• Difficulty starting the engine
• Foul odor or black smoke from the exhaust (due to unburned fuel)
• Decrease in engine power
• Car hesitates during acceleration
• Excessive fuel consumption due to an affected fuel trim

Can I Still Drive?

You should stop driving immediately if your vehicle’s Check Engine Light is on due to the P0302 cylinder 2 misfire code. 

The P0302 trouble code is a serious issue. If a misfire code is left unaddressed, it could affect your engine efficiency and cause a rough idle. It can even lead to ignition failure or catalytic converter damage, which is a costly repair. 

Misfires can also result in dangerous driving conditions. Your vehicle may stop abruptly and leave you stranded on the road.

P0302 Causes

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:

• Worn or damaged spark plugs, spark plug wire, or spark plug connector
• Failing or damaged ignition coil or faulty coil connector
• Distributor failure or damaged distributor cap
• Faulty fuel injector
• Vacuum leak
• Low fuel pressure
• Defective crankshaft position sensor 
• Distributor rotor button damage
• Engine timing is off
• Leaking head gasket
• Low engine compression
• Old or contaminated fuel
• Clogged EGR valve or tube
• Burned or sticking valve
• Worn or weak piston ring
• Valve cover gasket damage
• Faulty mass air flow sensor
• Bad oxygen sensor
• Faulty throttle position sensor (located on the throttle body)
• 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.

Diagnosis

Multiple reasons could trigger a code P0302 misfire, including damaged spark plugs, a bad ignition coil, or a defective fuel injector. 

Here’s how a certified technician will diagnose the root cause of the P0302 engine code:

1. They’ll first use an OBD-II scan tool to ensure no other related trouble codes are present. If the PCM registers any related trouble codes, they’ll fix them first.

2. If P0302 is the only code present, they’ll physically examine the ignition system. They’ll check for any loose connector or damaged wiring in the ignition coil. They’ll look for any loose engine ground wire as well.

3. Next, they’ll visually inspect the spark plug in cylinder 2 and the spark plug wire for any wear or carbon build-up that could prevent the ignition spark. They’ll clean the spark plug or replace it with a new plug. They’ll also test the resistance of the spark plug wire using a multimeter.

4. If your vehicle uses an ignition coil pack, they’ll swap the coil from cylinder 2 to a different cylinder. They’ll clear the code and test drive your car. If the misfire moves to the other cylinder, the coil is faulty and is responsible for the trouble code P0302.

5. Next, they’ll ensure that your engine is getting a sufficient amount of fuel. They’ll check for low fuel pressure, which could be due to a faulty fuel pump, fuel injector, fuel injector wire, or fuel pressure regulator.

6. If the ignition and fuel systems seem okay, they’ll perform a leak-down and compression test. This test helps check if a mechanical problem like a broken valve or worn piston ring induces the engine misfire causing the P0302 cylinder 2 misfire trouble code.

7. If the P0302 trouble code is still undiagnosed, a problem with the powertrain control module is possible.

Possible Repairs for P0302 & Costs

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

This DTC P0302 code repairs begin with an hour of diagnosis time, costing around $75-$150.

Once the root cause for the P0302 code is diagnosed, your mechanic may suggest one of the following replacements or repairs:

• Spark plug replacement: $100-$500
• Vacuum leak: $100-$200
• Spark plug wire replacement: $180-$240
• Ignition coil replacement: $200-$650
• Fuel pressure regulator: $200-$400
• Fuel pump replacement: $800-$1,300
• Powertrain control module replacement: $800-$1,500
• Fuel injector replacement: $800-$1,500
• Distributor rotor button and cap replacement: $100-$300
• Valve cover gasket replacement: $100-$350

Note: Costs for fixing issues related to this trouble code are average estimates. They may vary based on your location and the vehicle’s make and model.