Who knows how to interpret an auto zone read out?

Question

I went to auto zone and had my car scanned. They gave me four problems that I have listed below. Obviously I have more than one problem. But which one is more important? And which one should I replace first?

P0306 - a misfire has occurred in cylinder #6.

Definition:

Cylinder misfire detected - cylinder #6.

Explanation:

The power train control module monitors the crankshaft speed and had detected a misfire

condition.

Probable causes:

1. Ignition system fault

spark plug(s).

ignition switch.

wire set.

ignition coil.

2. Vacuum leak.

3. Injector fault.

4. High or low fuel pressure.

P0401 - there is insufficient flow in the exhaust gas recirculation system.

Definition:

EGR system fault (exhaust gas recirculation).

Explanation:

The ECM has detected too little flow on the EGR system.

Probable causes:

1. Blocked passage on EGR system.

2. Failed EGR valve.

3. EGR solenoid faulty.

4. Failed EGR pressure sensor.

P0443 - a malfunction exists in the electrical circuit for the purge control valve in the evaporative emission control system.

Definition:

EVAP (Evaporative Emission System) purge/vent solenoid circuit condition.

Explanation:

The solenoids and system wiring are monitored for opens or shorts.

Probable causes:

1. Purge or vent solenoids defective.

2. Check connector and wiring.

3. Fuel saturated vapor canister.

4. Failed EVAP vent solenoid.

P0500 - a malfunction exists in the electrical circuit for the vehicle speed sensor.

Definition:

Vehicle speed sensor malfunction.

Probable Causes:

1. Open or short circuit condition.

2. Poor electrical connection.

3. Failed VSS.

Answer 1

Does the vehicle regularly miss? I would start there, replacing plugs and wires. If that doesn't do it, you may have a bad injector.

Next thing would be to replace the egr, or take it off and clean it with seafoam

Answer 2

You didnt state wht kind of vehicle you are working on. These codes are very common on ford cars.#1 replace the spark plug wires. #2 check the hoses between the egr tube and the dpfe senso one or both are probably broken.#3 check vacuum lines and wiring for the evap system.#4 replace speed sensor.

Answer 3

I would not let Auto Zone scan my car, they are wrong way to many times. They do not even get close.

Answer 4

Misfire for sure. As it says you should probably at least check your #6 spark plug wire & spark plug, if that doesn't work check your #6 injector.

VSS is probably the least important since last I checked the VSS does nothing but make your dash and cruise control work  and if you can live without them it's better to focus on things relative to your engine.