P0306 code definition
Cylinder 6 detected with ignition error
What does the code P0306 mean?
P0306 is a generic OBD-II code that indicates that the engine control module (ECM) has detected an ignition error in cylinder number 6 of the engine.
What causes the P0306 code?
- The spark plug will not ignite on cylinder #6 due to contamination or broken insulation.
- The ignition coil on cylinder #6 stopped igniting due to broken insulation or open circuit.
- The spark plug wire or plug cap has a jump in the ignition spark to ground in cylinder #6 due to age.
- The valve cover has an oil leak in the spark plug holes and a short in the spark plug ignition on cylinder #6.
- The cylinder has low compression problems due to defective rings or valves.
What are the symptoms of the P0306 code?
- The Check Engine light will come on, and the code will be stored in the ECM memory.
- The Check Engine Light will flash when a misfire occurs.
- The engine will not ignite and may jerk or wobble when accelerating.
- The engine will lack power during acceleration when misfire is active and may affect gear changes.
How can a mechanic diagnose the P0306 code?
- Scan the codes and document the freeze frame data to verify the problem.
- Clean the engine and ETC codes and perform a road test to see if the problem recurs.
- Remove the cylinder 6 ignition coil or spark plug wire and check for signs of spark on the outside of the coil or spark plug housing. Also look for oil contamination through a leaking valve cover.
- Remove the spark plug from cylinder number 6 for inspection and replacement if necessary.
- Check engine cylinder compression if no ignition problems are found.
Most common errors when diagnosing P0306 code
- Do not translate the coil to another cylinder to see if the misfire will transfer to another cylinder. This would indicate a defective coil.
- Do not replace one part at a time with another cylinder to isolate the defective part.
How serious is code P0306?
- An improperly ignited cylinder can cause the engine to run too rich and can damage the catalytic converter.
- Ignition failure will cause the engine to run poorly and hesitate when accelerating.
- The engine will consume more fuel due to misfire.
What repairs can repair a P0306 code?
- Replace the faulty spark plug or replace all spark plugs together if the cause of the fault is a worn spark plug.
- Replace the leaking valve cover gasket, then replace the coil, spark plug wires and defective spark plugs.
- Replace ECM for bad circuit or fuel injector power coil for #6.
Additional comments on the consideration of code P0306
Code P0306 is triggered when the crankshaft sensor does not properly receive crankshaft acceleration from firing cylinder number 6, indicating that the cylinder is not contributing to engine power.
