P0302 code definition
Cylinder 2 misfire detected
What the P0302 code means
Most vehicles have either 4 or 6 cylinders. Each cylinder fires a spark plug one after another. A spark plug is located on the top of each cylinder. The spark plug uses an electric spark to ignite the flammable air/fuel mixture, producing energy.
The energy released by the fuel combustion powers the crankshaft. All of the cylinders work together to regulate the rotation of the crankshaft. As each cylinder fires, the crankshaft is able to rotate continuously. This process is what what makes the vehicle run smoothly.
The crankshaft revolutions per minute (RPM) may increase or decrease if a cylinder misfires. If the percentage of that increase or decrease becomes greater than 2 percent, the powertrain control module will store a trouble code.
If the crankshaft revolutions per minute have increased or decreased between 2 percent and 10 percent, the Check Engine Light will come on. If the crankshaft revolutions per minute have increased or decreased more than 10 percent, the Check Engine Light will blink. A blinking Check Engine Light indicates a more serious misfiring problem. The P0302 trouble code is an indication that cylinder 2 is misfiring and is not getting the necessary spark to its spark plug.
What causes the P0302 code?
- Defective spark plug in cylinder 2
- Lack of compression in cylinder 2
- Damaged or worn out spark plug wires and/or coils
- Damaged or worn out distributor cap (does not apply to all vehicles)
- Damaged or worn out rotor button (does not apply to all vehicles)
- Defective fuel injectors
- Clogged EGR valves or tubes
- Burned valves
- Ignition timing that is inaccurate
- Vacuum leaks
- Low fuel or low fuel pressure
- Leaking head gasket
- Damaged distributor cap
- Bad camshaft sensor
- Bad crankshaft sensor
- Bad mass air flow sensor
- Bad oxygen sensor
- Bad throttle position sensor
- Bad catalytic converter
- Bad powertrain control module
What are the symptoms of the P0302 code?
- Check Engine Light that is on or flashing
- Car will not start or is difficult to start
- Car hesitates during acceleration
- Engine that runs rough or idles rough
- Car has a lack of power while driving
- Car dies or stalls while stopped
- An increase of fuel consumption
How does a mechanic diagnose the P0302 code?
Uses the OBD-II scanner to collect freeze frame data and trouble codes stored by the powertrain control module
Checks to see if the P0302 trouble code comes back by test driving the car
Inspects the spark plug wire for cylinder 2 for wiring that is worn out or damaged
Inspects spark plug cylinder 2 itself for excessive wear or damage
Inspects the coil pack wires for wiring that is worn out or damaged
Inspects the coil packs for excessive wear or damage
If necessary, replaces damaged spark plugs, spark plug wires, coil packs, and coil pack wiring
If the P0302 trouble code returns after replacing any damaged spark plugs, coil packs, spark plug wires, and coil pack wiring, they will inspect the fuel injectors and fuel injector wiring for damage.
For vehicles with the distributor cap and rotor button system (older vehicles), they will inspect distributor cap and rotor button for corrosion, cracks, excessive wear, or any other damage.
Diagnose and repairs any other related trouble codes stored by the powertrain control module. Conducts another test drive to see if the P0302 trouble code comes back again.
If the P0302 trouble code returns, an inspection of the cylinder 2 compression system will be done (this is not common).
If the P0302 trouble code is still unresolved, a problem with the powertrain control module is possible (this is not common). Replacement or reprogramming may be necessary.
Common mistakes when diagnosing the P0302 code
Visually inspect the fuel injector wiring for damage before replacing spark plugs, coil packs, or spark plug and coil pack wiring. If applicable, diagnose and repair any other related trouble codes that are present. Also make sure to rule out a faulty cylinder as the cause of the problem.
Any of these components could result in the P0302 trouble code. It is important to take the time to rule out all possible causes of the misfire code during diagnosis. Addressing them during this process will save a lot of time.
How serious is the P0302 code?
The P0302 trouble code is considered serious. Some of the symptoms of this code make the operation of the vehicle dangerous. The vehicle may stop abruptly or stall out. In addition, damage to other engine components is possible if the trouble code is left unaddressed. For these reasons, the P0302 trouble code requires immediate attention.
What repairs can fix the P0302 code?
- Replacing spark plugs that are defective or damaged
- Replacing spark plug wires that are damaged
- Replacing coil pack wires that are damaged
- Replacing EGR valves or tubes if they are clogged
- Replacing valves that are burned
- Repairing any vacuum leaks
- Repairing or replacing leaking head gaskets
- Replacing camshaft sensor if defective
- Replacing crankshaft sensor if defective
- Replacing mass air flow sensor if defective
- Replacing oxygen sensor if defective
- Replacing throttle position sensor if defective
- Replacing fuel injectors that are defective
- Replacing catalytic converter if defective
- Diagnosing and repairing any related trouble codes stored by the powertrain control module
- Replacing distributor cap and rotor button, if defective and applicable to the vehicle
- Repairing defective internal engine components
- If there is cylinder damage, replace the engine
- In rare cases, the powertrain control module may need to be replaced or reprogrammed
Additional comments for consideration regarding the P0302 code
When one of the spark plugs needs to be replaced, replace the other spark plugs as well. If one of the coil packs needs to be replaced, it is not necessary to replace the other coil packs as well. This type of code is usually an indication that the car needs a tune up, so replacing one spark plug will normally not resolve the problem.
In order to make a quick determination about whether a faulty wire or coil pack is causing the misfiring problem, switch the wires or coil pack for cylinder 2 with another cylinder’s wires or coil packs. If a trouble code for that cylinder is stored by the powertrain control module, this indicates that the wire or coil pack is causing the misfire. When other trouble codes related to the misfiring issue are present, these need to be diagnosed and repaired as well.
Be sure that the spark plugs have been properly gapped. Use a feeler gauge to ensure a precise gap between the spark plugs. Failing to accurately gap the spark plugs, will result in another misfire. The spark plugs should be gapped according to the specifications set by the manufacturer. These specifications can usually be found on a sticker under the hood of the vehicle. If not, these specifications can be obtained from any local auto part store.
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