So I had AutoZone check with a code reader. They said it was a P0300. Should I take to the dealer or ?

Asked by Jul 31, 2012 at 02:17 PM about the 1997 Mazda MX-5 Miata Base

Question type: Maintenance & Repair

They said it could be The folowing...
Lean air/fuel ratio, week ignition system,engine mechanical condition, vacuumleak effecting one cylinder.
That was the print out they gave me. What to check first.

3 Answers


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. 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.

2 of 2 people found this helpful.

^ Exactly, if you are mechanically inclined it may be a good idea to tear into it a little and start replacing the vacuum lines on the car. possibly even a tune up too. probably be less than 175 for a full tune up and vacuum lines. just remember have good diagrams or take pictures if you feel unsure!

1 of 1 people found this helpful.

The 03 codes also include o2 sensor if im not mistaken. Most likely a bad o2 sensor...

1 of 1 people found this helpful.

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