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Toyota Repair/2001 toyota corolla idle problems: follow up


Yes the check engine light is on. I found a neighbor that had a diagnostic tool so I checked it and I got the codes P0300 P0303 and P0304 what should I start to replace?

Hello, there are two fairly common problems, spark plugs and ignition coil packs, remove the plastic cover from the engine and inspect the engine harness wires carefully including the fuel injector connectors and wring for any signs of damage from rodents. Remove the coils and inspect the insulators for burning or arcing, remove the spark plugs and replace them if in doubt. Clear the codes by disconnecting the battery for about a minute, drive it and if the same codes come back remove the #3 coil and switch it with #1, clear codes and drive it again, the check engine light will come back and if the codes now show P0301 and 304 replace both #1 and #4 coil packs.

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Ted Ritter


I have more than 28 years experience as toyota technician, I will be able to answer most questions related to the Toyota product line up to the present year models,I am located in the US but welcome questions from other regions of the world. When asking a question please provide specific information: year,model, engine,transmission information. Provide as much information as possible including a brief repair history if possible. I have been a volunteer here for more ten years an have answered over 16,000 questions helping Toyota owners with their problems and save thousands of dollars without any compensation, some of my answers are published on many other websites including google and various automotive forums. DONATIONS ARE VERY MUCH APPRECIATED, IF YOU HAVE RECIEVED HELPFUL INFORMATION PLEASE MAKE A DONATION. AS OF TODAY (JULY 22, 2014) ALL REQUESTED GRAPHICS, ILLUSTRATIONS, DIAGRAMS, PHOTOS, WILL REQUIRE THE MINUMUM DONATION UP FRONT.


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