Author: Ray Magliozzi-Car Talk
I bought a 1996 Toyota Land Cruiser last year. The local Toyota dealer found the "code PO306" for "6 cylinder misfire". He swapped the plugs between the five-cylinder and six-cylinder, and the misfire shifted to the five-cylinder.
Should I change the plug? I am an old lady and know very little about cars. Thank you for your suggestion. -Mary
Mary, I want to thank you for asking the simplest question I have encountered in 10 years. Would you please write it once a week? You and your dealer have completed all diagnostic work.
I think your Land Cruiser is not running smoothly, so you take it to the dealer. They scanned your car and the computer told them there was a fire in the six-cylinder. The next step is to find out why.
So the dealer did a very clever and simple test. He removed the spark plug from the sixth cylinder and put it in the fifth cylinder. Look, the problem is the spark plug. Now the five-cylinder ignition fails. So he knew it was the spark plug problem.
This also allowed him to rule out wiring problems, compression problems, and the possibility that someone left the screwdriver in your No. 6 cylinder during your last repair.
All he had to do at that time was to replace the spark plug, charge you $850 for diagnosis, and then send you on the road.
Now, something may be contaminating the spark plug, but I assume your mechanic has checked and ruled it out. It is more likely that your spark plugs have not been replaced since 1996 and the ceramic insulation of one of them has broken.
If this is the case, I recommend replacing all of them at this time. Replacing all six at the dealership may cost you approximately $300. These plugs are about $25 each, and because there is an air hose and several plastic covers at the rear end of the plug, they will charge you an hour's work fee. But this should solve the problem, Mary. Enjoy your land crusher.
Have questions about cars? Write to Car Talk Write to King Features of Ray, 628 Virginia Drive, Orlando, FL 32803, or send an email by visiting the Car Talk website www.cartalk.com.
Have questions about cars? Write to Car Talk Write to King Features of Ray, 628 Virginia Drive, Orlando, FL 32803, or send an email by visiting the Car Talk website www.cartalk.com.
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