CodelampTwo codes together
P0300 and P0302 together: misfires, worst in cylinder 2
P0300
- In plain words
- More than one cylinder, or no single one, is misfiring.
- Standard name
- Random/Multiple Cylinder Misfire Detected
- System
- Ignition and misfire
P0302
- In plain words
- Cylinder 2 is misfiring.
- Standard name
- Cylinder 2 Misfire Detected
- System
- Ignition and misfire
General information, not a mechanic's diagnosis: have a mechanic confirm before any repair.
What the computer saw
P0300 means misfires in more than one cylinder or no single one. P0302 names cylinder 2. Together they usually mean cylinder 2 misfires most, and the random code comes from it or from smaller misfires elsewhere.
Likely causes, most common first
- The spark plug or coil on cylinder 2. The most common cause of a single-cylinder code. Swapping the coil with another cylinder shows whether the misfire follows it.
- Worn spark plugs in general. Old plugs can miss in several cylinders, worst in one.
- A vacuum leak near cylinder 2. An intake leak close to one cylinder leans it more than the rest.
- The fuel injector on cylinder 2. A clogged or failing injector.
- Low compression in cylinder 2. Less common; found with a compression test.
What you can note yourself
- Note whether the light is steady or flashing, and tell the shop.
- Note when the plugs and coils were last changed.
What to tell the shop
- Both codes and whether the light flashed.
- Ask whether the misfire follows a swapped coil before parts are replaced.
This page gives no verdict on whether a car is safe to drive; a mechanic can.