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Tonchy 3/31/2021

2002 Toyota Highlander Base 6 Cyl 3.00L


How to fix codes p0300, p0302, p0304, and p0306

Hi, I have a 2002 Toyota Highlander base 3.0L 6cyl. I am having an issue where I originally had five codes that included the four in the question and a p1354. I replaced the variable valve timing solenoid for bank two with one from Standard Motor Products and the code went away; however, the four codes for the misfire still persisted. I then bought spark plugs and changed them out to no avail. I was wondering if I should try to replace the ignition coils or take it to a shop to see if something else is the issue.

1 Answer


Jimm 4/4/2021

For the misfires:P0300, P0302, P0304 and P0306...

It may mean that one or more of the following has happened:

Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer

Possible Solutions

If there are no symptoms, 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.


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