Question 1

What is the P0300 code definition?

Accepted Answer

Random or multiple cylinder misfire detected

Question 2

What does the DTC P0300 mean?

Accepted Answer

The DTC P0300 sets when the engine control module (ECM) detects the engine has one or more cylinders misfiring. A misfire happens when the air/fuel mixture inside a cylinder fails to ignite properly, resulting in no combustion or incomplete combustion in that cylinder. The ECM watches each cylinder's contribution by monitoring changes in the crankshafts rotational speed. When it sees the crankshaft slow down on a cylinder's firing event it registers it as a misfire. If the number of misfires exceeds an acceptable limit the ECM will set a P0300.

Question 3

What Causes P0300 to Set?

Accepted Answer

Ignition system malfunction, fuel system issue, incorrect air flow, exhaust system restrictions, mechanical engine failure, or falsley detected misfire

Question 4

How to diagnose P0300 DTC?

Accepted Answer

Determine which cylinder is misfiring, check ignition system, check fuel system, inspect intake/MAF, check exhaust for restrictions, test the engine for mechanical issue, and relearn crankshaft position sensor variation

Question 5

How do I repair a P0300 DTC?

Accepted Answer

If a faulty component is found by following the testing above, replace the component and re-evaluate your engine misfire.  If your P0300 is still present or was not diagnosed by following the diagnostic checks, more in-depth and intrusive testing will be needed to pin-point the cause.  As listed above there are several complex systems involved in the operation of a modern engine and guessing could become costly.