Error P0302 – how to fix?

Code definition P0302

Misfire detected on cylinder 2

What does the code P0302 mean

Most vehicles have 4 or 6 cylinders. Each cylinder fires one spark plug after another. There is one spark plug at the top of each cylinder. A spark plug uses an electric spark to ignite a flammable air / fuel mixture, generating energy.

The energy released by burning the fuel drives the crankshaft. All cylinders work together to regulate the rotation of the crankshaft. During the combustion of each cylinder, the crankshaft can rotate continuously. It is this process that ensures the smooth operation of the vehicle.

Crankshaft Rotations Per Minute (RPM) may increase or decrease when one of the cylinders fails. If the percentage of this increase or decrease is greater than 2 percent, the powertrain control module will record a fault code.

If the crankshaft RPM increases or decreases between 2 and 10 percent, the Check Engine indicator light will illuminate. If the crankshaft RPM increases or decreases by more than 10 percent, the Check Engine light will flash. A flashing Check Engine light indicates a more serious misfire problem. Error code P0302 indicates that cylinder 2 is misfired and the spark plug is not receiving the proper spark.

What causes the code P0302?

• Defective spark plug in cylinder 2
• No compression in cylinder 2
• Damaged or worn spark plug wires and / or solenoids.
• Damaged or worn distributor cap (not applicable to all vehicles)
• Damaged or worn rotor knob (not applicable to all vehicles)
• Faulty fuel injectors
• Clogged EGR valves or lines
• Blown valves
• Ignition time inaccurate
• Vacuum leaks
• Low fuel level or low fuel pressure
• The cylinder head gasket is leaking
• Damaged manifold cap
• Faulty camshaft sensor
• Faulty crankshaft sensor
• Defective air mass sensor
• Defective oxygen sensor
• Damaged throttle position sensor
• Faulty catalytic converter
• Faulty powertrain control module

What are the symptoms of the P0302 code?

• The engine light comes on or flashes
• The car does not start or is difficult to start
• The car hardly accelerates
• Engine runs sluggish or idling
• The car has no power while driving
• The car stops or stops when stationary
• Increased fuel consumption

How can a mechanic diagnose the P0302 code?

• It uses an OBD-II scanner to collect data from frozen frames and fault codes stored by the powertrain control module.
• Check that fault code P0302 reappears while driving the car.
• Inspect cylinder 2 spark plug wire for worn or damaged wiring.
• Inspect the spark plug in cylinder 2 for wear or damage.
• Inspect the coil pack wires for worn or damaged wires.
• Inspect coils for excessive wear or damage.
• If necessary, replace damaged spark plugs, spark plug wires, coil packs, and coil pack wiring.
• If fault code P0302 returns after replacing damaged spark plugs, coil packs, spark plug wires, and coil pack wiring, inspect the fuel injectors and fuel injector wiring for damage.
• For vehicles with a distributor cap and rotor button system (older vehicles), they will inspect the distributor cap and rotor button for corrosion, cracks, excessive wear, or other damage.
• Diagnose and repair any other related fault codes stored by the powertrain control module. Take another road test and check that fault code P0302 reappears.
• If fault code P0302 reappears, the cylinder 2 compression system must be checked (not common).
• If trouble code P0302 remains unresolved, there may be a problem with the powertrain control module (not common). May need replacement or reprogramming.

The most common errors when diagnosing the P0302 code.

Before replacing spark plugs, coil packs, or wiring to spark plugs and coil packs, visually inspect the fuel injector wiring for damage. If applicable, diagnose and repair any other related trouble codes that are present. A defective cylinder should also be ruled out as the cause of the problem.

Any of these items can cause trouble code P0302. It is important during the diagnosis to exclude all possible causes of the appearance of the ignition error code. Addressing them during this process will save a lot of time.

How serious is the P0302 code?

Error code P0302 is considered serious. Some of the symptoms of this code make the vehicle unsafe to operate. The vehicle may stop suddenly or stall. In addition, other engine components may be damaged if the fault code is not cleared. For these reasons, fault code P0302 requires immediate attention.

What repairs can fix the code P0302?

1. Replace faulty or damaged spark plugs.
2. Replace damaged spark plug wires
3. Replace damaged coil pack wires
4. Replace clogged EGR valves or EGR lines
5. Replace any blown valves
6. Repair vacuum leaks
7. Repair or replacement of leaking cylinder head gaskets
8. Replace the camshaft sensor if it is damaged
9. Replace the crankshaft sensor if it is damaged
10. Replace the mass air flow sensor if it is damaged
11. Replace the oxygen sensor if it is damaged
12. Replace the throttle position sensor if it is damaged
13. Replace fuel injectors if damaged
14. Replace the catalytic converter if it is damaged
15. Diagnose and repair any related fault codes stored by the powertrain control module.
16. Replace the distributor cap and rotor button, if damaged and applicable to the vehicle
17. Repair of damaged internal engine components.
18. Replace the engine if the cylinders are damaged.
19. In rare cases, it may be necessary to replace or reprogram the powertrain control module.

Additional notes regarding code P0302

When one of the spark plugs needs to be replaced, the other spark plugs must also be replaced. If one of the coil packs needs to be replaced, it is not necessary to replace the remaining coil packs. This type of code is usually an indication that the car needs servicing, so replacing one spark plug does not usually solve the problem.

To quickly determine if the misfire problem is due to a damaged wire or coil pack, replace the wires or coil pack from cylinder 2 with wires or coil pack from another cylinder. If the powertrain control module records an error code for that cylinder, the wire or coil pack is the cause of the misfire. If there are other misfire error codes, they should also be diagnosed and repaired.

Make sure spark plugs are properly fractured. Use a feeler gauge to ensure accurate spark plug spacing. Inaccurate positioning of the spark plugs will cause another misfire. Spark plugs must be fractured according to the specifications provided by the manufacturer. These specifications are usually found on a sticker under the hood of the vehicle. If not, these specifications can be obtained from any local auto parts store.