If there are no symptoms (symptoms may include: the engine may be harder to start; the engine may stumble / stumble, and/or hesitate), the simplest thing to do is to reset the
code and
see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating,
check
all wiring and connectors that lead to the cylinders (i.e. spark
plugs). Depending
on how long the ignition components have been in the car, it may be a
good
idea to replace them as part of your regular maintenance schedule. I
would
suggest spark plugs, spark plug wires, distributor cap, and rotor (if
applicable).
Otherwise, check the coils (a.k.a. coil packs). In some cases, the
catalytic
converter has gone bad. If you smell rotten eggs in the exhaust, your
cat converter
needs to be replaced. I've also heard in other cases the problems were
faulty
fuel injectors.
Random misfires that jump around from one cylinder to another (read:
P030x
codes) also will set a P0300 code. The underlying cause is often
a lean fuel
condition,
which may be due to a vacuum leak in the intake manifold or unmetered
air getting
past the airflow sensor, or an EGR valve that is stuck open.
A MISFIRING may mean that one or more of the following has happened:
- Faulty spark plugs or wires
- Faulty coil (pack)
- Faulty oxygen sensor(s)
- Faulty fuel injector(s)
- Burned exhaust valve
- Faulty catalytic converter(s)
- Stuck/blocked EGR valve / passages
- Faulty camshaft position sensor
- Defective computer
With one scanner you can know exactly what cyl is misfiring. Tell us news.
